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Combination motor flow divider designed to simplify component synchronization.

For years hydraulic system designers have been faced with the problem of synchronizing two or more movements which are not mechanically linked. Examples include controlling two hydraulic cylinders to travel at the same speed or rotating two motors at the same speed regardless of loading.

There have been a number of possible solutions that have been developed to address the problem. Gear type flow dividers are one of the most used remedies, but they result in efficiency losses, added bulk and expense. Other possible solutions include dedicated pumps for each actuator, pressure-compensated flow controls, series circuits, servo valves with closed loop feedback and a multitude of others, all of which have their drawbacks.

In order to offer a solution to some of these issues, Rineer Hydraulics, in conjunction with Risley Equipment Ltd., Grande Prairie, Alberta, Canada, has developed a combination motor flow divider designed to simplify speed synchronization. At the heart of the product is a vane-crossing-vane, rotor-stator package which consists of working vanes in the rotating member and sealing vanes in the stationary member.

The stationary element has four working cavities separated by stator vanes, creating four independent working elements which are common to the output shaft. Basically, it can be considered as four independent hydraulic motors in a parallel circuit connected to a common shaft, according to the company.

The motor flow divider receives flow which is equally divided between each cavity and discharge flow from two cavities is directed to the normal outlet port, thus defining the motor section. Discharge oil from the remaining two cavities is directed to a second output port, providing flow to the auxiliary function.

As an example, a 15 cu.in./rev displacement package would function as a 7.5 cu.in./rev displacement motor while providing an equal 7.5 cu.in./rev to the auxiliary circuit. Assuming the secondary function is a 7.5 cu.in./rev motor, both output shafts would rotate at approximately the same speed. The use of a smaller or larger displacement motor in the auxiliary function may be used to obtain different speed ratios between devices, the company said. When both outlet ports are vented to tank, the device functions as a 15 cu.in./rev motor.

To accommodate a wider range of auxiliary flow requirements, a split displacement stator may be selected, Rineer said. This type stator has two different size cavities resulting in two dissimilar displacements. One example currently being used is a 10.5 cu.in./rev configuration, in which two opposed cavities displace 7.5 cu.in., while the other two cavities produce 3 cu.in.

The split displacement stator package was originally developed for Risley Equipment, a leading manufacturer of timber-harvesting equipment, including delimbers, feller bunchers, saw heads and whole tree processors. The split displacement motors are used on Risley's intermittent cut saw heads for feller bunchers and on its whole tree processors. Both machines include a low-speed circular saw for felling trees. Risley's feller buncher saw head includes an accumulator arm which allows multiple stems to be harvested before stockpiling is required, while the processor fells, delimbs and cuts to length single trees or multiple stems, depending on the model.

In operation, both machines loosely clamp onto the tree to hold it in a vertical position. Once the tree is secured, the saw circuit is activated with the secondary port diverted to tank, delivering the full torque of 10.5 cu.in./rev to insure fast blade acceleration. When maximum speed has been achieved, the secondary circuit is diverted to the feed circuit. Two hydraulic cylinders then power the rotating saw head into the cut. In order to prevent blade stalling due to overcrowding by the feed cylinders, blade speed and feed rate must be synchronized. The 10.5 cu.in./rev split displacement motor divider was selected, with 7.5 cu.in./rev driving the blade rotation while 3.0 cu.in./rev powers the two feed cylinders.

In operation, should blade speed decline due to loading or variations in pump flow, cylinder feed rate will decrease in direct proportion, Rineer said. This, according to the company, virtually eliminates time loss from blade stalling, increasing productivity even with less experienced operators. Other advantages to the Risley intermittent cut and feed system include lower horsepower requirements, less regeneration growth damage and reduced operator fatigue.

The motor divider is a birotational device, however the flow dividing is effective in one direction only. When operated in the opposite direction, the unit functions as a full displacement motor.

The Rineer motor divider is currently available in the company's 15 series line. Standard displacements of 6 cu.in., 7 cu.in., 8 cu.in., 9.5 cu.in., 13 cu.in./rev and 15 cu.in./rev Split displacements include 10.5 cu.in./rev and 11.5 cu.in.

Other possible applications include drill rotation with synchronized feed rate, synchronizing planer infeed and outfeed rolls and synchronizing vehicle ground drive and cutter heads.
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Title Annotation:Rineer Hydraulics
Comment:Rineer Hydraulics and Risley Equipment Ltd have developed a new combination motor flow divider for simpler speed synchronization.
Publication:Diesel Progress North American Edition
Geographic Code:1CANA
Date:Aug 1, 1999
Words:831
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