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General operations.

Electric motors are most commonly used in fixed applications where alternating current is available, although motors are available for field use. In the public works arena, electric motors are commonly used to drive pumps and other machinery in water and wastewater facilities. Sizeable electric motors are manufactured by Dynapac Light Equpt.; GE Co.; Ideal Electric Co.; Lincoln Electric Co.; Ronk Electrical Industries, Inc.; Franklin Electric.

A-1.196 Electric Generator Sets

Electricity for lighting or power in the field and during SECTION A-1



PUBLIC works fleets basically contain construction equipment, automobiles, and trucks. Since all equipment will eventually wear out even if given the best care, how do you know when to replace it? Do I purchase, do I rent, or do I lease?

When to replace. Lane County, Oregon developed a computerized model that selects equipment for replacement by comparing the mean annual cost of owning and operating each existing unit in the fleet to the projected costs of its potential replacement. Factors considered in the analysis are:

* Current and future market values of the existing and proposed unit.

* Operating cost of both units.

* Downtime costs.

* User equipment needs.

* Obsolescence.

* Interest rates.

Lane County's approach is unique in several ways. For example, it identifies a unit for replacement when its total cost is greater than that of a new unit. Some systems merely identify units for replacement when they have passed their economic prime, regardless of the cost for a new unit. This approach also takes into account user equipment needs and planned usage, variables that have a major effect on the replacement decision. Other systems assume that usage is constant and can therefore be ignored. Lane County also can consider different makes and models of equipment for a replacement purchase and can analyze the rebuilding option.

The computer prepares a "cost and performance profile" for each equipment class, showing trends in fuel use, repairs, and downtime by year of age, based on historical dates. County staff then reviews each profile and modifies it as needed to reflect the expected performance of a replacement unit of that class. For example, if recent improvements in fuel efficiency are expected to decrease consumption by ten percent, then the trend data on the profile is reduced accordingly.

Next, the following data are entered on each profile:

* Planned usage.

* Current market values of the equipment.

* Price of fuel.

* Hourly cost of downtime.

* Shop labor rate.

The computerized model then calculates the mean annual cost of owning and operating a replacement unit, based on the profile and input data, and compares it to the current annual cost of each existing unit in that class. This results in a replacement analysis report. Each current unit in the class is listed, along with its cost components. An "annual cost" column compares the costs of the current and new units. An asterisk appears at the far right of the report whenever the "old" annual cost exceeds that of the "new," indicating a candidate for replacement.

County staff then reviews and evaluates the report. If any data appear off, they are investigated. Also, any units the county does not want to replace, either because they are no longer needed by the user or for other non-economic reasons, are deleted from further replacement consideration. The computer program then generates a replacement list showing all units warranting replacement in order of priority; the highest replacement priorities go to the units that represent the greatest loss in relation to optimum cost.

The State of Oregon's Department of Forestry determines replacement by using a point system. The department evaluates a vehicle based on four criteria: operating cost per mile (fuel costs, maintenance costs, and overhead costs divided by miles), age, mileage, and condition of the vehicle's body and mechanical components. The department then compares these findings to its own standards for how a similar vehicle should be performing and assigns a rating to each vehicle criterion based on how it compares to the standard.

The ratings are low, base (equal to the standard), high, and extreme. Points are assessed according to which rating a particular criterion was assigned--1 point for "low," 2 points for "base," 3 points for "high," and 4 points for "extreme." Any point total exceeding 8 indicates that the department should take a hard look at replacing the vehicle.

Consolidated Edison, a New York City-based utility, determines replacement using five criteria: lifetime maintenance costs, age, mileage, current condition, and the cost of retaining the vehicle for an additional year.

Maintenance cost data excluding accident damage and preventive maintenance, as well as vehicle age and total miles driven, are compared to the target values established by the company for that type of vehicle. These target values give the optimum replacement age for that vehicle type, the cost to purchase a replacement, the number of vehicles of that type that should be replaced each year, and the optimum mileage for a vehicle of the age being considered.

Depending on how the vehicle's actual maintenance cost, age, and mileage data compare to the company's target values, the vehicle is assigned to one of 11 categories that indicate replacement priority. Priority 1 represents the highest replacement priority while Priority 11 represents the lowest. Following are the replacement priorities:

Priority 1. Maintenance dollars have exceeded 75 percent of replacement cost, and vehicle has met or exceeded age and mileage criteria.

Priority 2. Maintenance dollars have exceeded 75 percent of replacement cost, and vehicle has met or exceeded mileage criteria.

Priority 3. Maintenance dollars have exceeded 75 percent of replacement cost, and vehicle has met or exceeded age criteria.

Priority 4. Maintenance dollars have exceeded 75 percent of replacement cost.

Priority 5. Maintenance dollars have exceeded 50 percent of replacement cost, and vehicle has met or exceeded age and mileage criteria.

Priority 6. Maintenance dollars have exceeded 50 percent of replacement cost, and vehicle has met or exceeded mileage criteria.

Priority 7. Maintenance dollars have exceeded 50 percent of replacement cost, and vehicle has met or exceeded age criteria.

Priority 8. Maintenance dollars have exceeded 50 percent of replacement cost.

Priority 9. Vehicle has met or exceeded both age and mileage criteria.

Priority 10. Vehicle has met or exceeded mileage criteria only.

Priority 11. Vehicle has met or exceeded age criteria only.

How do I replace? Beyond the warranty, equipment acquired through outright purchase following the low-bid process basically becomes the owner's responsibility. Items to consider when planning an outright equipment purchase include extent and duration of the warranty; dealer or distributor backup, reputation, and parts inventory; and the municipality's ability to handle its own maintenance and repairs in addition to the possibility of stocking sufficient parts to further reduce downtime.

Many municipalities have had bad experiences with the low-bid process and have turned to total cost bidding or life cycle costing. The concept is simple enough. In broad terms, it consists of a net-cost bid that starts with the bid price of the equipment, then adds a guaranteed maintenance cost over an agreed-upon service life, and finally subtracts a guaranteed buy-back or trade-in figure.

Life cycle costing considers long-term after-purchase factors including operating and repair costs, life expectancy, and the disposal value of the equipment. Municipalities often require that bids include a maximum repair guarantee, resale value, anticipated operational costs (including fuel use), and investment cost. Bid winners are then selected on the lowest cost per hour of operation for the county.

With ever tightening budgets, municipalities require maximum use of their equipment. If a heavy piece of equipment cannot be extensively used and winds up sitting for large portions of time, it may be cheaper in the long run to rent it, thereby avoiding expenses like the initial purchase price, maintenance expenses, and associated labor costs. This would be particularly true if a specific piece of equipment was needed for a specific short term project. In the case of counties and states, renting equipment may also help avoid the expenses incurred when certain pieces of equipment must be transported long distances for short term projects. Leasing may not be that popular with government fleets for several reasons. First, most leasing contracts generally cover more than one year, and public agencies are frequently restricted from entering into multi-year contracts. So a city can really only commit to paying the first year of an agreement. The city cannot promise the people who are loaning it the money that it will be able to pay the second and third years. Because administrations change from one election to the next, a state or local government cannot mortgage the future to save the present by piling up massive obligations. The city can do it with bonds, but only after voter approval.

To accommodate these special circumstances, every lease purchase agreement has a "fiscal funding" clause that lets the government walk away from its obligations if funds are not appropriated for the contract each year. So who would lend money under these conditions? Lenders can tell if a city is well managed and in good financial shape. The city also knows that if it capriciously decides to walk out on a deal, it will have an extremely hard time finding another lease purchase agreement.

The lender in a lease purchase agreement is also protected by a "non-substitution" clause, which says that if the city walks out on the last two years of the deal, it cannot buy, borrow, rent, or steal the same equipment from any source for any reason for the remainder of the agreement's term. At the same time, if the city is experiencing severe financial problems, it can get out of the lease.

Those who purchase bonds do not risk losing money because of budget cuts in later years. When someone buys a bond, they are paid the interest and principal promised--guaranteed. Because of the threat of non-appropriation, lease purchase interest rates are often higher than bond rates. However, because a lease purchase agreement is not considered long-term debt and, therefore, is not subject to voter approval, it offers a much faster route to acquiring needed equipment.

Other drawbacks to leasing include: In the case of automobiles, major leasing companies prefer working with fleets that need 25 vehicles or more, so smaller fleets are forced to turn to new or used car dealers that charge higher rates for less volume. And municipalities have traditionally bought on the basis of the lowest qualified bid. Finally, many local governments count on the money from the resale of used vehicles and equipment as a way to reduce the overall fleet budget.

However, leasing can lower maintenance costs since the leasing company is responsible for repairs and service. And leasing does not require the full capital outlay that purchasing does. According to the Department of Fleet Management, Knoxville, Tennessee, leasing may be a feasible alternative of equipment replacement if any of the following conditions are typical for your municipality:

* Capital funds for equipment replacement have low priority and funding is unpredictable from year to year.

* The tendency is to retain equipment beyond its useful life.

* Equipment acquired is suitable for leasing or lease purchase.

* There is an inability to recover fair market value of surplus equipment because of legal restrictions or local market conditions.

Leasing is offered under various names, including closed end lease, open end lease, finance lease, municipal lease, residual lease, lease purchase, and municipal lease purchase. Each is a variation or combination of three basic lease types: closed end lease, open end lease, and lease purchase.

Conceptually, closed end or fixed residual leasing may be considered as "rental" of the useful life of the equipment. Typically, the residual value, which is the estimated market value of the equipment at the end of the lease term, is fixed at the beginning of the lease term. Penalties are assessed at lease end for excessive mileage or poor condition beyond normal wear and tear. Ownership under a closed end lease usually resides with the lessor, and the equipment is returned to the lessor at the end of the lease. A "buy out" option is often offered to the lessee at the stated residual value. As such, the lessee incurs no capital investment and builds no equity in the equipment. From the perspective of equipment management the normally "fixed" cost of depreciation is converted to a controlled operating expense.

Other characteristics of closed end leases include predictable costs and typically lower total term payments because equity is not purchased. Equipment suitable for closed end leasing includes vehicles with good resale value such as sedans, pickups, and medium-duty trucks with dump or stake bodies. Specialized and emergency equipment usually are not available through closed end leasing. Generally, mileage restrictions will apply to protect the lessor's equity investment.

The primary advantages of closed end leasing to municipalities lies in the risk-free nature of the closed end lease. The total lease costs are fixed up front, with the lessor assuming all risk for the recovery of the residual value at lease end. Another advantage is that the municipality pays finance costs only on the depreciated portion of vehicle actually used (purchase price less residual value). Closed end leasing helps a scheduled vehicle replacement program since the vehicle must be replaced or purchased at lease end. Closed end leasing--because of the need to control wear and tear and mileage--also fosters good fleet management practices.

Closed end leases typically have a slightly higher monthly payment than other lease types, as the lessor must assume the risk of residual value, but result in a lower total term cost liability--an important consideration for municipalities.

The main difference between open end and closed end leasing lies in the residual risk factor. In open end leasing, the lessee is responsible for recovering the residual value of the vehicle at lease end. Typically the lessee would be faced with two choices, buy the equipment at the stated residual value or liquidate the equipment. Normally, any profit over the residual value after liquidation is given to the lessee. However, any loss under residual value must be made up by the lessee. Open end leasing can perhaps be best thought of as installment financing with a balloon payment at the end.

Other than the risk factor associated with the residual value, open end leases are structured similar to, and carry many advantages and disadvantages of, closed leasing. The main advantage of the open end lease is that it typically offers lower monthly payments than a closed end lease. However, the lessee should be aware that some lessors will set unrealistically high residual values to offer low monthly payments. The lessee is then faced with a large lump sum payment or liability at lease end. The residual liability of an open end lease, and so the inability to determine a total lease cost, tends to make open end leasing a less attractive alternative to municipalities.

Municipal lease purchase is nothing more or less than tax exempt installment financing. Title is vested in the lessee with the lessor as lien holder. Equity is built in the equipment, which becomes the unencumbered property of the lessee with the final payment. Because title is vested in a tax exempt entity--the municipality--the lessor can offer finance rates often lower than prime interest, which is typically not true for the other lease types. Usually any type of municipal equipment can be purchased through this method. It is the flexibility of equipment choice, low interest rates, and the ability to spread capital acquisition costs over several fiscal periods that have led to the increasing popularity of lease purchase in the public sector. However, lease purchase is not without drawbacks. Usually, lease purchase payments are higher than with other lease types as equity must be purchased in the equipment. Sometimes lease purchase terms may be longer than the useful life of the equipment, reinforcing the tendency to retain cost-prohibitive units. Typically, few services are offered with lease purchase agreements--especially if procured through a financial institution. The lessee may possibly be faced with problems of acquisition and disposal of equipment and offered little help in the control of fleet costs.

In general, there are three components of leasing costs under any type lease. These are depreciation, finance charges, and administrative charges. Depreciation is the purchase price less residual and is usually prorated on a straight line formula. Lessors usually offer municipalities a "pass through" purchase cost, which includes any fleet discounts, incentives, or rebates that the lessor may be granted. The purchase price obtained is quite often less than one the municipality can secure through competitive bids. Finance components of the lease depend on the lease type, lease term, make and type of equipment, and current prime interest rate. Finance rates are usually tied to a proportion of prime interest and may be either fixed for lease term or float with prime interest or some other index.

The third part of the lease charge is the administrative cost of the lessor to initiate and administer the lease. This typically amounts to about 0.01 percent of the purchase price of the equipment per month.

To determine whether a municipality should lease, one must compare the cost of leasing to the current method of equipment replacement. Obviously, any form of financing, including leasing, results in a greater total acquisition cost than cash purchase. The real issues are if leasing lowers total fleet costs per fiscal period and stabilizes those costs. One must examine and project the cost of leasing over a multi-year period based on these factors: purchase cost, lease payment, potential operating and maintenance savings from using new equipment, downtime cost reductions, and income from surplus property sales. Each municipality must develop a comparative model based on its requirements and conditions. The major lessors can and will assist these cost analyses by providing current lease rate factors, sample proposals, and vehicle selector guides.

A-1.10 Fleet Financing

State and local governments are offered equipment and facilities funding by Baker Equpt. Leasing Co., Inc.

A-1.100 Automobile & Equipment Fleet Sales/Leasing

Ford Motor Company; Hertz Equipment Rental Corp. offer automobile sales services. Baker Equpt. Leasing Co. Inc.; Global Rental Co., Inc.; Hertz Equipment Rental Corp.; Utility Equpt. Leasing Corp. rent equipment especially selected for communications, construction, and maintenance.

A-1.11 Loaders

Crawler loaders are used as prime movers for other construction equipment; as pushers to assist the forward movement of other equipment in heavy going; as carriers of blades of various types for use in bulldozing, leaf collection, and solid wastes handling; as snowplows under some circumstances; and in some instances as carriers of fork lift devices for handling suitable materials. Crawler loaders provide greater flotation than wheel units and, thus, are desirable for use on soils that are soft or loosely packed.

Selecting the proper track option for your crawler loader can make a big difference in your productivity. Whether you need to do fine grading, traverse slopes, or work in poor underfoot conditions, undercarriage options can help to pull you through efficiently and profitably. According to Komatsu Dresser Company, before looking seriously at a particular undercarriage configuration, however, it is best to carefully analyze the types of jobs you work on. In other words, do not "overspec" your equipment for the tasks at hand.

Long-tracks. Long-track models are most frequently used where fine grading is essential. The extended track frame helps smooth out variations in grade, while standard-width track shoes provide good maneuverability. In many cases, a first-rate operator will be able to grade as well with a standard-track crawler as with a long-track crawler. But an average operator would do a better and more efficient job of grading with longer tracks. Long-track versions are also well-suited for dozing heavier loads while the blade is in the full-angle position. The longer track frame gives the machine better stability. And, if you attach a larger blade, the extra roller offsets the increase in blade weight.

Wide tracks. Wide track models economically deliver a low center of gravity and stable stance, letting them work slopes efficiently. Using a standard length undercarriage with a wider track gauge and overall track width, wide track crawlers also spread the machine's weight over a greater surface area for improved flotation in mud, snow, and other soft ground conditions. In certain cases, this can make the difference between being able to work in marginal conditions and getting stuck. On small crawler tractors, wide tracks may be up to 60 percent wider than standard shoes. On larger machines, they typically offer an improvement in shoe width of 30 percent. Typical applications of wide track crawlers include grading highway shoulders and banks around sedimentation and fire ponds.

Low ground pressure. Low ground pressure (LGP) models combine the longer track length of a long track model and the wide track shoes of a wide track machine to provide maximum flotation in soft or swampy conditions. While operators of LGP machines sacrifice some maneuverability, they pick up a significant increase in flotation.

Lubricated track system. Some manufacturers offer a lubricated track system as standard equipment on their long-track, wide-track, and low ground pressure models. Internal lubrication extends track life, simplifies repairs, results in quieter running machines and, in most applications, reduces hourly under-carriage costs. In a lubricated track system, the space between the pin and the bushing receives constant lubrication. A seal assembly keeps the pin and bushing surfaces lubricated with oil at all times, minimizing internal pin and bushing wear. Lubricated track systems are recommended even on standard-track crawlers, since replacing these parts is labor intensive and can involve significant downtime. Ideally, the lubricated track system should feature a split master link design, which reduces chain removal and installation time and does not require a special track shoe.

Construction equipment manufacturers now offer many sizes of tractors, crawler sizes and undercarriage options to suit almost every application. Consider them all, but remember to stay realistic. Focus on how you plan to use the new machine 90 percent of the time. For example, if long tracks will only come in handy for a small percentage of your work, you are probably better off with standard tracks--and not just from a cost standpoint. Long tracks can hinder your machine's performance on jobs that require excellent maneuverability. However, if your goal is to expand into additional jobs that involve extremes in underfoot conditions--whether rocky, hilly, or swampy--then you should take a harder look at various track options.

Wheel loaders are used in many of the same tasks as crawler loaders. They give increased speed and maneuverability in good underfoot conditions. When used in sanitary landfills they are frequently fitted with special wheels to avoid the potential for punctured tires. They are more suitable for use on paved surfaces because the rubber tires they are fitted with do not damage the pavements.

A-1.110 Crawler Loaders

Crawler loaders are manufactured by Bombardier, Inc., Industrial Equipment Div.; J I Case Co.; Caterpillar Inc.; John Deere; Hydra Mac, Inc.; Komatsu Dresser Co.

A-1.111 Wheel Loaders

Wheel loaders are manufactured by Brown Bear Corp.; Caterpillar Inc.; J I Case Co.; JCB Inc.; John Deere; Komatsu Dresser Co.; Kubota Tractor Corp.; M-B Companies Inc., Power Broom Div.; O & K Trojan; Omni Equpt. Corp.; SWR (Solid Waste Retriever); TCM America, c/o M.M.D., Construction Equpt. Div.; TEREX Div.; VME Sales North America; White-New Idea Farm Equpt. Co.

A-1.112 Skid-Steer Loaders

Small wheel loaders that employ skid steering and are useful in confined quarters are manufactured by Ford New Holland, Inc., Public Affairs; Gehl IC Group; Hydra Mac, Inc.; J I Case Co.; John Deere; M-B-W, Inc.; Melroe Co./Bobcat, A Business Unit of Clark Equpt.; Mustang Mfg. Co., Inc.; Prime Mover Co.; Thomas Equpt. Ltd.; Trak Int'l.

Skid-steer loader attachments like scrap/demolition buckets, pulpwood/forklift combinations, specialty buckets, and grapple assemblies are available from Alitec Corp.; Attachments Int'l.

A-1.113 Multi-Purpose Tractors

These small wheel tractors often feature enclosed cabs, maneuverability, and the ability to handle several attachments, including plows, blades, compactors, snowplows and blowers, brooms, street flushers, backhoes, sewer cleaners, etc.

They are available from Bombardier Inc., Industrial Equpt. Div.; Holder of North America; M-B Companies, Power Broom Div.; Mercedes-Benz of N. America, Inc.; Omni Equpt. Corp.; SMI Industries USA Inc.; Trackless Vehicles Ltd.

All-terrain vehicles that can move small amounts of equipment around job and construction sites are available from Polaris Industries L.P.

A-1.12 Integral Loaders

Integral bucket loaders are workhorses on public works projects. They excavate, stockpile, and load stone, gravel, and sand; maintain stockpiles of critical chemicals for snow and ice control purposes; grade; and for numerous other purposes. The loader is perhaps the basic unit in the public works equipment fleet, apart from the dump truck with which it teams. Teamed with a backhoe attachment, the integral loader is among the most popular, widely-used pieces of construction equipment.

Integral loaders are manufactured by Athey Products Corp.; Caterpillar Inc.; Continental Diversified Sales, Inc.; Eagle Crusher Co., Inc.; Ford New Holland, Inc., Public Affairs; J I Case Co.; John Deere; Komatsu Dresser Co.; Liebherr-America, Inc.; M-B Companies, Inc., Power Broom Div.; Melroe Co./Bobcat, A Business Unit of Clark Equpt.; Prime Mover Co.; Samsung Heavy Industries Co., Ltd.; Terramite Corp.; VME Sales North America.

Athey Products Corp. has force-feed belt-type loaders that handle sold and berm, leaves, snow, solid waste, and sludge.

A-1.13 Bulldozers

Bulldozers are used for light land clearing, for moving earth short distances, for backfilling, and in sanitary landfills for spreading solid waste and cover materials, and to some extent for reducing bulk volumes. Manufacturers of bulldozers include J I Case Co.; Caterpillar Inc.; John Deere; Komatsu Dresser Co.; Liebherr-America, Inc.; Samsung Heavy Industries Co., Ltd.

A-1.14 Attachments

Loaders, dozers, and tractors can be equipped with attachments that make the basic unit a multi-purpose machine. Among the manufacturers of these attachments are:

Backhoes--Ajusta-Buckets, Inc.; Alitec Corp.; American Trencher, Inc./Bradco; Attachments Int'l.; Continental Diversified Sales, Inc.; Dig-It Mfg., A Div. of Spancrete Machinery Corp.; Ditch Witch; Ford New Holland, Inc., Public Affairs; Hydra Mac, Inc.; J I Case Co.; JCB Inc.; John Deere; Melroe Co./Bobcat, A Business Unit of Clark Equpt.; Terramite Corp.; Vermeer Mfg. Co.; Wain-Roy, Inc.; Woods Div., Hesston Corp.

Loaders--American Trencher, Inc./Bradco; American Coupler Systems, Inc.; Attachments Int'l.; Balderson Inc.; Caterpillar Inc.; Dig-It Mfg., A Div. of Spancrete Machinery Corp.; Esco Corp.; Gill Mfg. Co., L.P.; Guest Industries, Inc.; J I Case Co.; John Deere; M-B Companies, Inc., Power Broom Div.; Major Equpt. Co., Inc.; Omni Equpt. Corp.; PB Loader Corp.; Sweepster; Vermeer Mfg. Co.; Wain-Roy, Inc.; Werk-Brau Co., Inc.

Fork Lift Tines--Easily attached steel tines to convert bucket loaders to fork lifts are manufactured by American Coupler Systems, Inc.; Attachments Int'l.; Coleman Methods Corp.; Construction Technology, Inc. (CTI); Guest Industries, Inc.; Major Equpt. Co., Inc.

Coupler Systems--Ajusta-Buckets, Inc.; American Coupler Systems, Inc.; Attachments Int'l.; Balderson Inc.; Caterpillar Inc.; Henke Mfg. Co.; Major Equpt. Co., Inc.; Rockland Mfg. Co.; Wain-Roy, Inc.; Werk-Brau Co., Inc. have couplers with which loaders can be equipped with specialized tools, blades, buckets, forks, industrial brooms, or snowplows and blowers for various jobs confronting public works agencies.

Graders--Attachments Int'l.; Front Runner Corp.

Grapples--Attachments Int'l.; Werk-Brau Co., Inc.

ROPS Structures--Roll over protection structures for tractors and loaders are manufactured by Sims Mfg. Co.

Rippers & Scarifiers--American Coupler Systems, Inc.; Balderson Inc.; J I Case Co.; Caterpillar Inc.; Guest Industries, Incorporated.

Blades/Cutting Edges--Blade attachments and replacement cutting edges for tractors, graders, bulldozers, scrapers, etc. are available from American Trencher, Inc./Bradco; Attachments Int'l.; Balderson Inc.; Bucyrus Blades, Inc.; Caterpillar Inc.; Curtis Tractor Cab Inc.; Esco Corp.; Haban Mfg. Co.; J I Case Co.; John Deere; Kenco Engineering, Inc.; Kennametal Inc., Mining and Metallurgical Div.; Kubota Tractor Corp.; Pacal Blade Div., Paper, Calmenson & Co.; Rockland Mfg. Co.; Tuff Parts Inc.; Valk Mfg. Co.; Valley Blades Ltd.

A-1.15 Excavation Equipment

Hydraulic excavators are used extensively for trenching for water lines or sewerage or storm drains, as well as to excavate for underground structures. Many hydraulic excavators are so designed that they may also be used to ditch, for ditch cleaning, and for policing embankment slopes. They may also be used, with appropriate added attachments, for backfill compaction and pavement breaking and removal.

Power shovels and cranes are used to excavate and stockpile on the job and in the yard; to develop drainage facilities; and for materials handling between grades. With appropriate buckets, the machines may be used to remove unwanted materials in reservoirs and lagoons.

A-1.150 Hydraulic Excavators

Hydraulic excavators are manufactured by Akerman Inc.; Badger Construction Equpt. Co.; Caterpillar Inc.; Daewoo; Gehl IC Group; Gradall Co.; J I Case Co.; John Deere; Karo Works; Koehring Cranes & Excavators; Komatsu Dresser Co.; Kubota Tractor Corp.; Liebherr-America, Inc.; Link-Belt Construction Equpt. Co.; Little Giant Crane & Shovel Co.; Melroe Co./Bobcat, A Business Unit of Clark Equpt.; Menzi U.S.A. Sales, Inc.; O & K Trojan; R. A. Hanson, Inc.; Samsung Heavy Industries Co., Ltd.

A-1.151 Power Shovels & Cranes

Power shovels, hoes, and cranes are manufactured by Badger Construction Equpt. Co.; Liebherr-America, Inc.; Link-Belt Construction Equpt. Co.; Little Giant Crane & Shovel Co.; Manitowoc Engrg. Co.; O & K Trojan.

A-1.152 Buckets

Buckets for shovels and draglines are manufactured by Ajusta-Buckets, Inc.; Attachments Int'l.; Erie Strayer Co.; Esco Corp.; J. Gannon Mfg. Co., Inc.; J I Case Co.; Major Equpt. Co., Inc.; RWF Industries; Wain-Roy, Inc.; Werk-Brau Co., Inc.

Backhoe buckets specifically designed for excavating shot rock, demolition debris, and other tough, abrasive material are available from Esco Corp.; Gannon Mfg. Co., Inc.; Werk-Brau Co., Inc.

Ditch cleaning buckets are for ditch maintenance and construction; not useful in grading and slope work or designed for tough digging applications. They are available from Werk-Brau Co., Inc.

Material handling buckets for handling or loading irregular shaped objects or debris can be obtained from Gannon Mfg. Co., Inc.; Werk-Brau Co., Inc.

Multi-purpose buckets for light grading, backfilling, material handling, and loading are made by Gannon Mfg. Co., Inc.; Werk-Brau Co., Inc.

Pavement removal buckets designed to load large pre-cut slabs of pavement are available from Werk-Brau Co., Inc.

Quick coupler buckets designed to change from one attachment to another are made by Werk-Brau Co., Inc.

Skid-steer buckets can be obtained from Attachments Int'l.

Tilt buckets are designed to enhance the machine's grading capability. The bucket can be tilted 45 |degrees~ in either direction enabling the operator to maintain a level trench with the machine at an angle. They are available from Werk-Brau Co., Inc.

The "PowerTilt" Bucket and Tool Positioner provides 70 |degrees~ left and right bucket and tool swing positioning capabilities for backhoes and excavators under 50,000 lb operating weight. It is available from Helac Corporation.

A-1.153 Bucket Teeth/Conical Points/Tines

Bucket and auger teeth, conical points, and various adapters are available from Esco Corporation; J I Case Company; Pengo Corporation.

A-1.154 Air Excavation Equipment

Air excavation equipment forces compressed air through a wand to remove or jet soil from around pipe, cable, and other buried services, enabling soil removal with no risk of damage to underground structures. Removed soil is contained by vacuuming. This equipment is available from Air Technologies Inc.

A-1.16 Hydraulic Cranes

Hydraulic cranes are important tools in several aspects of public works. In small versions (cherry pickers), they are invaluable in yard and storage areas. They are used to handle heavy and/or cumbersome lifts, as well as for receiving and loading materials. Large cranes, of course, are used for bigger jobs, as in the construction of structures.

Hydraulic cranes are manufactured by Auto Crane Co.; Badger Construction Equpt. Co.; Cargotec, Inc.; Iowa Mold Tooling Co.; Koehring Cranes & Excavators; Komatsu Dresser Co.; Link-Belt Construction Equpt. Co.; Little Giant Crane & Shovel Co.; Manitex Inc., A Subs. of The Manitowoc Co., Inc.; Manitowoc Engrg. Co.; Nu-Lift Products, Inc.; Paxton-Mitchell Co.; Petersen Industries, Inc.; Precision Husky Corp.; Stedt Hydraulic Crane Co.

A-1.17 Scrapers

Scrapers are used for excavation, transport, and redistribution of fill. They can do fine grading and may be used for windrowing materials for future use. Scrapers are frequently used on sanitary landfill operations to transport and stockpile cover material. Scrapers are manufactured by Automatic Equpt. Mfg. Co.; Caterpillar Inc.; John Deere; Komatsu Dresser Co.; RWF Industries; TEREX Div.

A-1.170 Elevating Scrapers

Elevating scrapers may be obtained from Caterpillar Inc.; John Deere; Komatsu Dresser Co.

A-1.18 Graders

The straight frame motor grader has always been a popular machine because of its year round productivity, versatility, and work-alone capability. Graders are often articulated and have advanced hydraulic systems to handle blading shoulders, smoothing washboards, working ditches, cutting banks, and blading cul-de-sacs.

Graders are manufactured by Athey Products Corp.; Caterpillar Inc.; Bob Fisher Enterprises Inc.; Champion Road Machinery Ltd.; Gehl IC Group; Huber Essick; Ingersoll-Rand Co., Road Machinery Div.; John Deere; Komatsu Dresser Co.; B. R. Lee Inc. d/b/a Lee-Boy Mfg. Co.; Mauldin Mfg. Co., Inc.; O & K Trojan.

A-1.180 Truck Underbody Blades

Blades to be attached beneath a truck body to give it grading/plowing capabilities are manufactured by Monroe Truck Equpt., Inc.; Valley Blades Ltd.

A-1.181 Grade & Slope Equipment

Slope Meter Co. has instruments that help operators maintain required slopes.

Rockland Mfg. Co. manufactures the Road King Sloper, a hydraulic rear-mounted moldboard for sloping and finishing.

A-1.182 Earth Drills & Augers

Large earth drills and augering equipment are used to drill various sized holes in earth for the purpose of setting sign standards, poles, etc. Some are self-powered with small gasoline engines; others act as attachments on loaders and skid-steer loaders and use the loaders' hydraulic systems for power. Manufacturers include Allied; Barrett Diamond Products, Inc.; DeepRock; Greenlee Fairmont; Kennametal Inc., Mining and Metallurgical Div.; Little Beaver, Inc.; McLaughlin Mfg. Co.; Stanley Hydraulic Tools; Terramite Corp.

A-1.183 Mud Tracks

Mud tracks are panels that are placed over muddy soil to permit heavy construction equipment to traverse the area without bogging down. Mud-Traks from SVE Sales are lightweight, flexible, fiber-mat 4-ft by 12-ft mud track panels that fold to 4 ft by 6 ft. They interlock as a continuous track and offer a traction grip surface.

A-1.19 Power Centers

Air and hydraulic compressors and tools, gasoline and diesel engines and tools, electric motors, and electric generator sets can be used to power an array of equipment at the job site.

A-1.190 Air Compressors & Tools

The variety of types, sizes, and features offered by portable compressor manufacturers makes it difficult for municipalities to decide what to specify or what is the best buy for their application. Before setting out to buy a compressor, it is imperative to understand job requirements and what is being offered.

The first and foremost consideration is the intended application and operating environment for the compressor. Both the compressor and the engine performance vary appreciably with ambient temperature, operating pressure, and altitude. The machine life is also adversely affected by a dusty or abrasive environment, extended operation at light loads or in an overloaded condition, and improper controls. You should clearly outline the probable operating environment before selecting an air compressor.

If the air drawn by the engine and compressor is laden with dust, insist on a two-stage air cleaner with service indicator. In very dusty atmospheres it may even be prudent to specify a pre-cleaner that would remove most heavy dirt particles and extend the air cleaner element's life. Nothing shortens the life of the machine and increases the cost of maintaining it more than dirt. It is critical to prevent dirt from reaching the compressor or engine for performance and safety considerations.

The three major types of compressors available are reciprocating, rotary sliding vane, and rotary screw. The reciprocating type compressors, available for over 50 years, are easy to service and do not require the oil system similar to the ones used on rotary models. The rotary compressors, however, seem to be the most popular designs available today.

Once you decide what type of compressors you want to buy, you must decide what its capacity should be based on the air consumption requirements of the tools you intend to operate. If you plan to purchase tools with the compressor, do not forget to check their air consumption specifications, making certain the compressor capacity exceeds the total consumption. You will seldom operate all the tools simultaneously. However, it is a good idea to size the compressor to match or exceed total required capacity to compensate for leaks, variations in operating speed, and the manufacturer's design tolerance for output (which should be plus or minus three percent of rated output).

Specifying operating pressure is an even more important consideration, as pressure relates directly to productivity. Efficiency and performance of air tools as well as sandblasting and pile driving equipment drop appreciably with loss of air pressure. If you expect to operate equipment through long hose lines, do not forget to consider pressure drop. It is important that the compressor be able to deliver rated capacity at pressure high enough to maintain desired working pressure at the point of use.

Generally, if a compressor is designed to operate at pressures up to 125 psig while delivering full capacity, you should be able to get 90 to 100 psig at the tool. Of course, higher operating pressure means higher fuel consumption. Therefore, it is always a good idea to keep the pressure drop to a minimum.

Perhaps the most critical selection is the engine. In a portable compressor package, especially the rotary screw compressor models, the engine requires more attention and maintenance than any other component. (It may go through as many as three complete overhauls before the rotary screw air end is opened up. Whereas the compressor may go for a year without having to change oil, separator, or filter, the engine may require an oil and filter change once a month.) Engine performance is also greatly affected by the load as well as ambient temperature, altitude, humidity, and type of fuel. Fuel cost can also be a substantial portion of the operating costs. All these factors point to the need for careful evaluation of the available engine choices.

Since most compressors sold are built with diesel engines, this discussion will be geared toward them. The same basic criteria for compressor selection also applies to those buying gasoline engines.

Diesel engines fall into two categories: air-cooled and watercooled. Both types have advantages and disadvantages. Before specifying the make or type, check what warranty is available on the engine, who the engine dealer is nearest you, and what his reputation is for parts sales and service. It is also a good idea to compare prices of typical service parts.

Naturally aspirated engines lose their power at higher ambient temperatures or altitudes. As a rule of thumb, they should be derated by one percent for every 10 |degrees~ F rise in ambient temperature above 85 |degrees~ F and three percent for every 1,000 feet elevation above 500 feet. Turbocharged engines generally do not lose power as rapidly as naturally aspirated engines do at higher altitudes, and should therefore be preferred for operation at altitudes above 5,000 feet.

Power reserve is the difference between the rated output of the engine (based on intermittent or continuous rating, as the application dictates) and the brake horsepower of the compressor plus power consumed by accessories such as cooling fan, alternator, pump, etc. The engine will lose power much more rapidly than the compressor as altitude increases. Consequently, an engine with very little reserve at sea level will be overloaded at 3,000 to 5,000 feet elevation. Also, as an engine wears out, it will develop less horsepower, and overloading will accelerate engine wear. As a rule of thumb, you should specify at least 20 percent reserve power.

Another important consideration in specifying power reserve is the required operating pressure. If you expect to operate the compressor at pressures above 100 psi, make sure you know what the compressor BHP is at higher operating pressures, and what the power reserve is at that pressure. The rule of thumb here is that the compressor BHP goes up by 1/2 percent for every 1 psi increase in discharge pressure.

There are other considerations that may help you select an engine that offers more value for your money:

* Turbocharged engines run quieter and are more fuel efficient.

* With more cylinders, the engine will run smoother, especially at idle speeds.

* It is not uncommon to see diesel engines running on full load at speeds in the 2,500 to 3,600 rpm range; speeds that suit the rotary compressors just fine. Higher engine speed may eliminate the need for gears in the compressor.

* There are two different types of engines being used in portable compressors--industrial and automotive. As the name suggests, automotive types are designed for trucks or passenger cars. They may go 100,000 miles between overhauls, but those miles translate into about 2,500 to 4,000 hours in an application such as compressors. Industrial engines, on the other hand, are designed for 10,000 to 15,000 hours of life before they require a major overhaul.

Almost all portable compressors utilize an air end bolted directly to the engine. The direct coupling, however, does not mean that the compressor runs at the same speed as the engine.

Manufacturers prefer the gear drive arrangement because it gives them the flexibility to offer a wider range of capacities with a limited number of rotor sizes. It also lets them use smaller rotors for a given capacity and operate them at speeds higher than the maximum allowable engine speed. Another benefit of gear drive is the ability to optimize rotor speed to achieve lowest possible power consumption.

A major drawback of a geared drive arrangement is that the smaller size of the air end also means smaller bearings running at higher speeds. The bearings in a smaller air end will not last as long as ones in a slower running, larger air end. All considerations being equal, preference should be given to packages utilizing larger air ends running at slower speeds.

Compressing air generates heat, and this heat must be dissipated as quickly and efficiently as possible. Reciprocating compressors are generally air cooled, using heat exchangers between stages as well as after the final stage. If the air in a reciprocating compressor is compressed in one stage, the discharge temperature could go as high as 450 |degrees~ to 500 |degrees~ F. In a two-stage machine with cooling between stages it could be in the 250 |degrees~ to 300 |degrees~ F range. An aftercooler can bring the discharge temperature down to within 10 |degrees~ to 15 |degrees~ F of the ambient.

In a rotary screw type or sliding vane compressor, air is cooled while it is being compressed by injecting oil in the cylinder. The design of the oil cooler in a portable compressor resembles the engine radiator. Common practice is to use the same fan for cooling both the oil cooler and the radiator, however, air-cooled engine models require a separate fan for cooling compressor oil.

Of the two fan types available, suction and blower, the blower type fan is preferable, as it keeps the compressor enclosure close to ambient temperature. The suction type fan on the other hand, draws air through coolers, resulting in as much as a 40 |degrees~ F temperature increase in the air.

This rise in air temperature causes the enclosure to become a "hot box," adversely effecting the performance and life of components such as hoses, control lines, rubber seals, electric wires, filters, etc.

Since oil serves several critical functions in a rotary compressor, keeping its properties intact over a long period of time is vital to the compressor's life. Heat affects oil more than anything else. In the rotary compressor, oil goes through heating and cooling cycles several times a minute, which can amount to almost 2,000 cycles in a day. Petroleum based oils oxidize rapidly at temperatures above 180 |degrees~ F, (the average temperature during a cycle in the rotary compressor). The maximum oil temperature can go as high as 230 |degrees~ F. Oil also goes through shearing action in the compressor, and it can pick up incoming dirt and other contaminants during every cycle.

To prolong the life of the oil (and keep maintenance costs lower), the system should assure that:

* Air and oil filters can trap contaminants as small as 25 microns or less.

* Maximum oil temperature is kept as close to 180 |degrees~ F as possible.

* Oil goes through the heating/cooling cycles as few times as possible.

To achieve these results, you should specify 1) full flow oil filter with a minimum 25 micron rating, 2) heavy duty two-stage air cleaner with a 10 micron rating, 3) 125 |degrees~ F ambient capability, and 4) oil reservoir large enough to limit the number of cycles.

It is worth remembering that once oil starts oxidizing and is contaminated, it can affect bearings in the compressor as well.

Safety considerations and federal, state, or local regulations can have considerable influence on undercarriage selection. Generally, portable compressors up to and including 375-cfm size are equipped with a two-wheel running gear. Larger sizes are built on four wheel running gears, either with a wagon type undercarriage that has a steerable front axle, or with a tandem axle type design with rigid frame and towbar. The latter type is becoming increasingly popular due to its high speed towing capability. The wagon type trailers cannot be towed at speeds over 15 mph. If you expect to tow the compressor frequently, specify highway towing speed capability.

If the compressor is expected to be towed on highways, make sure it is equipped with lights and/or brakes that satisfy state and local regulations.

When specifying or selecting the tires or axle for a portable compressor, remember that the undercarriage should be designed to carry not just the total weight of the standard machine, but also accessories and tools that might be required with it. Also note that tire ratings are affected by towing speeds. Another precaution is to specify safety chains between the main frame and towing vehicle.

Controls can be divided into two categories: operating controls to ensure smooth and efficient operation, and protective controls to prevent damage to the equipment in the event of malfunction.

Consumption of compressed air fluctuates widely, almost continually. The operating controls should therefore be specified to match the demand with the supply at any given moment. In an engine driven compressor, this is generally accomplished by throttling the compressor inlet valve and also regulating the engine speed. Slowing the engine down also helps reduce fuel consumption at partial load or no load. It is important to specify stepless modulating controls to ensure smooth operation of the machine at all loads.

It is also worth specifying no-load start and quick idle warmup. A no-load start device prevents the engine from starting with pressure in the compressor reservoir, prolonging the life of the engine starting system and preventing the engine from running backward.

You may also want to specify: vented filler cap on reservoir to warn the operator if the tank is still under pressure, low coolant level shutdown, fire extinguisher mounted on the machine, and velocity fuse on the service valve to shut the supply off if the hose fails.

A portable compressor can be fitted with numerous accessories to suit various individual needs. Some popular options often specified by public works departments are:

* Hose Reel. Capable of storing 500 or 100 feet of hose. These are generally mounted on the drawbar and add considerable weight to the hitch. It is advisable to specify an adjustable screw-type jack to adjust the height of the hitch for coupling and uncoupling.

* Lubricators. Pint, quart, or gallon capacity. If the compressor is to be used for operating air tools, a quart capacity oiler in each line should be adequate for a full shift operation.

* Rear bumper.

* Safety tow chains.

* Retractable pneumatic third wheel.

* Rear support (stabilizer leg).

* Instrument panel light (for nighttime operation).

* Cold weather starting aid. For ease of starting at ambient temperatures below 30 |degrees~ F. Also, ether shot should be a measured quantity, ignition switch operated, to prevent overloading the engine with ether and blowing it up.

Portable compressors are also used for sandblasting, where the operator may need breathing-quality air for his mask. It must be remembered that conventional oil-flooded compressors do not provide oil-free air, and should not, therefore, be used for that purpose, unless they are equipped with a special filtration system that complies with applicable OSHA regulations. Portable air compressors and/or tools are manufactured by Fuller Co.; Getec Inc.; Goldblatt Tool Co.; GrimmerSchmidt Compressors; Ingersoll-Rand Co., Portable Compressor Div.; Iowa Mold Tooling Co.; M-B-W, Inc.; LeRoi Int'l., Inc.; Maintainer Corp. of Iowa, Inc.; Mitsui Machinery Distribution, Air Products Div.; Multiquip Inc.; Quincy Compressor Div., Coltec Industries; Rhino Tool Co.; Service Trucks Int'l. Ltd.; Sullair Corp.; Sullair PTO, Vanair Mfg. Co.; TT Technologies, Inc.

A-1.191 Hydraulic Compressors & Tools

Hydraulic tools may be powered from hydraulic systems on equipment and trucks in many cases, or hydraulic power centers. Hydraulic power centers and/or tools are available from Allied; ENERPAC Unit of Applied Power Inc.; Greenlee Fairmont; Getec Inc.; Hydra-Tech Pumps, Incorporated.; Stanley Hydraulic Tool, Division of The Stanley Works; Stedt Hydraulic Crane Corporation.

A-1.192 Gasoline Engines

Gasoline engines are used to power a variety of public works equipment and installations. Gasoline engines are manufactured by Briggs & Stratton; Caterpillar Inc., Engine Div.; Chrysler Corp.; Geometric Results Inc., Power Products Div.; Hercules Engine Co.; Kawasaki Motors-Engine Div.; Kohler Co.; Waukesha Engine Div., Dresser Industries, Inc.; Ford Truck Operations; United Marine Int'l. Inc.

A-1.193 Gasoline Powered Tools

Gasoline engine powered rock drills and breakers are available from Atlas Copco Berema, Inc.

A-1.194 Diesel Engines

Heavier and more durable than gasoline engines, and able to use heavier, less refined fuels, diesel engines have become the norm in heavy equipment, as well as heavy and lightweight trucks. Diesel engines are manufactured by Caterpillar Inc., Engine Div.; Chrysler Corp.; Cummins Engine Co., Inc.; Deere Power Systems Group; Detroit Diesel Corp.; Deutz Corp.; Ford Truck Operations.; Ford New Holland, Inc., Public Affairs; Geometric Results Inc., Power Products Div.; Hatz Diesel of America, Inc.; Hercules Engine Co.; Lister-Petter Inc.; Mercedes-Benz of N. America, Inc.; Navistar Int'l. Transportation Corp.; Volvo GM Heavy Truck Corp.; Waukesha Engine Div., Dresser Industries, Inc.; Yanmar Diesel Engine (USA).

Diesel engine components including fuel injection equipment, turbochargers, engine brakes, and other engine accessories are available from Diesel Injection Service Company, Incorporated.

A-1.195 Electric Motors
COPYRIGHT 1993 Hanley-Wood, Inc.
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Copyright 1993 Gale, Cengage Learning. All rights reserved.

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Title Annotation:The 1993 Public Works Manual
Publication:Public Works
Article Type:Buyers Guide
Date:Apr 15, 1993
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