CN111456982A

CN111456982A - Precise hydraulic roller, hydraulic motor and low-speed high-torque hydraulic system

Info

Publication number: CN111456982A
Application number: CN202010242151.3A
Authority: CN
Inventors: 斯蒂芬·拉里诺夫·斯蒂芬诺夫
Original assignee: Yobaikos Bulgaria Ltd
Current assignee: Yobaikos Bulgaria Ltd
Priority date: 2020-03-31
Filing date: 2020-03-31
Publication date: 2020-07-28

Abstract

The invention belongs to the technical field of mechanical transmission, and discloses a precise hydraulic roller, a hydraulic motor and a low-speed high-torque hydraulic system, which comprises a driving assembly, wherein the driving assembly comprises a stator and a rotor, and each stator and each rotor are provided with a longitudinal axis; at least one of the stator and the rotor comprising a plurality of rollers, each of the rollers having a rounded outer surface and an end surface, the rounded surface of the roller defining a first set of teeth that mesh with a second set of teeth on the other of the stator and the rotor, the first and second sets of teeth defining expanding and contracting fluid chambers; and a fluid channel extends between at least one of the fluid chambers and at least one of the roll end faces and establishes fluid pressure communication. Performance, reliability, quality and cost are improved while meeting market demands, while providing the desired quality.

Description

Precise hydraulic roller, hydraulic motor and low-speed high-torque hydraulic system

Technical Field

The invention belongs to the technical field of mechanical transmission, and particularly relates to a precise hydraulic roller, a hydraulic motor and a low-speed high-torque hydraulic system.

Background

The slitter hydraulic motor receives pressurized fluid as an input and provides high torque rotary motion as an output. The gear sets of the hydraulic motor drive assembly collectively define a fluid chamber. The chamber expands when hydraulically connected to a source of pressurized fluid and contracts when connected to a drain that returns the fluid to the source. The expansion and contraction of the fluid chamber causes rotational movement. These motors are relatively small and efficient, and the rotational output is widely used to move and control various types of equipment. In many of these applications, an operator controls a source of pressurized fluid for a hydraulic motor. This controls the input to the hydraulic motor and thus the rotational output (speed and torque) of the hydraulic motor.

All current precision roll manufacturers for Geroller motors use rolls of 15.9825+/-0.0025 specified diameters. To ensure the uniqueness of our product and give us the freedom to design the rotor and stator sets used in our own hydraulic rail motor, we decided to use a different diameter 16.0000 and achieve greater control over the manufacturing and implementation process. As a positive effect we can get better performance and less friction, thus improving efficiency.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides a precise hydraulic roller, a hydraulic motor and a low-speed high-torque hydraulic system.

The invention is thus embodied in a precision hydraulic roll comprising a drive assembly comprising a stator and a rotor, each of said stator and said rotor having a longitudinal axis;

at least one of the stator and the rotor comprising a plurality of rollers, each of the rollers having a rounded outer surface and an end surface, the rounded surface of the roller defining a first set of teeth that mesh with a second set of teeth on the other of the stator and the rotor, the first and second sets of teeth defining expanding and contracting fluid chambers;

and a fluid channel extends between at least one of the fluid chambers and at least one of the roll end faces and establishes fluid pressure communication.

Further, the stator includes a plurality of roller cavities, each of the rollers is disposed in one of the roller cavities and provides the first set of teeth, and the rotor has a surface defining a second set of teeth.

Further, the longitudinal axes of the rotor and the stator are parallel and spaced apart.

Further, a plurality of fluid passages are included, and each of the plurality of fluid passages extends between one of the fluid chambers and one of the roll end faces and establishes fluid pressure communication.

Further, the number of the fluid passages, the rollers and the chambers is the same.

Further, a member is included adjacent the rotor and the stator, the fluid passage is at least partially within the member, the member and the rotor and the stator each include radial end faces, all of the end faces lie in a plane, and all of the planes are parallel.

Further, each of the rollers includes another end surface, and another fluid passage extends between one of the fluid chambers and one of the first-mentioned roller end surfaces and establishes fluid pressure communication.

Further, first fluid passages are included, each extending between and establishing fluid pressure communication between one of the fluid chambers and one of the first-mentioned roll end faces, each fluid passage having a second fluid passage. Extending between one of said fluid chambers and one of said other roll end faces and establishing fluid pressure communication.

Further, the first-mentioned plurality of fluid channels and the second-mentioned plurality of fluid channels are equal in number to the roller.

Further, the first set of teeth and the second set of teeth are operatively engaged along a line of contact separating each of the fluid chambers from each other and the fluid chambers are on one. The pressure level of each of the contact lines is higher than the other side of the contact line.

Further, each of the first fluid passages establishes substantially open hydraulic communication between the higher pressure level fluid chamber adjacent each of the contact lines and the end face of the first-mentioned roller defining the contact line, and each of the second fluid passages establishes fluid pressure communication between the higher pressure level fluid chamber adjacent each of the contact lines and the other end face of the roller defining the contact line.

Further, a first member is included, the first member including a surface adjacent the rotor and the stator and the roller, a second member including another surface adjacent the rotor, the stator and the roller. The fluid channel is at least partially within the first member and the other fluid channel is at least partially within the second member.

Further, the stator and the rotor and the first member each comprise a radial end face, the radial end faces of the stator, the rotor and the first member, and the first-mentioned end face of the roller are all parallel, the stator and the rotor and the second member each comprise another radial end face, and the stator, the rotor, the other radial end face of the second member, and the another end face of the roller are all parallel.

Further, the first fluid passage is at least partially defined by the radial end surface of the first member, and the second fluid passage is at least partially defined by the radial end surface of the second member.

Further, the first fluid passage is defined by a groove in the radial end face of the first member, and the second fluid passage is defined by a groove in the radial end face of the second member.

Another object of the present invention is to provide a hydraulic motor equipped with the precision hydraulic roller, comprising a driving assembly, a manifold and a wear plate:

wherein the drive assembly includes a stator and a rotor, each of the stator and the rotor having a longitudinal axis, the longitudinal axis of the stator being parallel to and spaced from the longitudinal axis of the rotor, each of the stator and the rotor having first and second end faces;

at least one of the stator and the rotor comprising a plurality of rollers, each of the rollers having a longitudinal axis substantially perpendicular to the longitudinal axis of the stator and the rotor, each of the rollers having a generally rounded outer surface and having first and second end faces, the rounded surfaces of the rollers defining a first set of teeth that mesh with a second set of teeth on the other of the stator and the rotor, the first and second sets of teeth defining expanding and contracting fluid chambers;

the manifold includes a surface adjacent the first end faces of the stator and the rotor, a plurality of working fluid passages extend through the manifold surface, each of the fluid chambers is in fluid pressure communication with at least one of the manifold fluid passages:

the wear plate includes a surface adjacent the second end faces of the stator and the rotor, and a fluid channel in at least one of the wear plate and the manifold, the fluid channel extending between and establishing fluid pressure communication between one of the fluid chambers and one of the first and second end faces of the roller.

Further, each of the manifold and the wear plate has at least one of the fluid passages.

Further, the number of fluid channels in each of the manifolds and the wear plates and the rollers is the same, each of the fluid channels in the manifolds establishing fluid pressure communication between one end face of one of the rollers and one fluid chamber adjacent the roller, and each of the fluid channels in the wear plates establishing fluid pressure communication between the other end face of one of the rollers and the fluid chamber adjacent the roller.

Further, the fluid channels in the manifold and wear plates in fluid communication with the first and second end faces of each respective roller are in fluid pressure communication with the same fluid chamber

Further, each of the channels in the wear plates is in fluid communication with the one end face of one and only one of the rollers, and each of the channels in the manifolds is in fluid communication with the other end face of one and only one of the rollers.

Further wherein the motor is assembled in a hydraulic circuit including a variable displacement hydraulic pump, the pump including an output control mechanism for manual retention and operation by an operator input. The hydraulic pump operates at a pressure level greater than 1000 psi, the hydraulic pump has a fluid pressure outlet hydraulically connected to the electric motor, and the electric motor operates at a speed of less than five revolutions per minute.

Another object of the present invention is to provide a low-speed high-torque hydraulic system mounted with the hydraulic motor, comprising:

a drive, manifold, wear plate and housing:

the drive assembly including a stator and a rotor, each of the stator and the rotor having a longitudinal axis, the longitudinal axis of the stator being parallel to and spaced from the longitudinal axis of the rotor, each of the stator and the rotor having first and second radial end faces, the first radial end faces being coplanar in a first plane perpendicular to the longitudinal axis, the second radial end faces being coplanar in a second plane parallel to the first plane;

said stator comprising a plurality of rollers each having a longitudinal axis perpendicular to the longitudinal axis of said stator and said rollers, each said roller having a rounded outer surface extending in the longitudinal direction of the roller and having first and second radial end faces coplanar with the respective first and second planes of said stator and said radial end faces of said rollers, said rounded surface of said rollers defining a first set of teeth effective to mesh with a second set of teeth on said other stator and said rotor, said rotor being in movement at a longitudinally extending contact line upon relative rotational movement of said stator and said rotor, radially adjacent teeth of said first and second sets of teeth defining expanding and contracting fluid chambers between circumferentially adjacent lines of movement contact, and during operation of said motor, the fluid chamber on one side of the contact line is at a higher fluid pressure level than the fluid chamber on the other side of the contact line;

the manifold includes a radial end face longitudinally immediately adjacent and parallel to the first radial end faces of the stator and the rotor, a plurality of fluid passages extend longitudinally through the manifold end face, each of the fluid chambers being in pressure communication with at least one of the manifold end face fluid passages:

the wear plate includes a radial end face longitudinally immediately adjacent and parallel to the second radial end faces of the stator and the rotor;

the housing includes an interior cavity, a drive link disposed in the interior cavity, and a mechanical connection to one of the stator and the rotor;

a plurality of anti-tooth bottom fluid passages in the wear plate radial end face and the manifold radial end face, the passages in the manifold radial end face establishing fluid communication between the fluid chamber on one side of each contact line and a first radial direction of a respective roller, the respective roller meshing with a radially adjacent tooth to define the contact line, and the passages in the wear plate radial end face establishing fluid communication between the fluid chamber and a second radial end face of the respective roller on the one side of the contact line.

Further, the number of fluid chambers, the number of rollers, the number of fluid channels in the wear plate, and the number of fluid channels in the manifold are all the same.

Further, the fluid channels in the wear plates and manifolds in communication with the first and second end faces of each of the rollers are open and closed to fluid communication at the same time for the same fluid chamber.

In summary, the advantages and positive effects of the invention are:

compared with the existing motor, the motor of the winding and cutting machine meets the market demand, improves the performance, reliability, quality and cost, and provides the required quality. Gerotor and Gerotor motors use the so-called track principle, which is why these motors have a huge power density and compact dimensions. A Gerotor rotor star has six teeth and seven cams. The space between them is a pressure chamber. The pump fluid flows into these chambers, creating a high pressure in one chamber and a low pressure in the other chamber. This creates a force imbalance that results in a rotational or orbital motion of the star configuration of the Gerotor rotor. A Gerotor rotor star configuration rotates multiple times (fig. 1), typically six to eight times, depending on the particular star and ring geometry, to achieve each complete single rotation within the outer ring. The Geroler motor uses a roller to replace a cam, so that friction and abrasion can be reduced, low-speed performance is improved, and the service life of the motor is prolonged. The Gerotor and Gerotor motors can provide 10 to 50000 inch pounds of torque and can operate at speeds up to 2000 RPM. They are useful for mobile and industrial applications due to their simple design and compact size. However, due to their incredible power density, they are well suited for mobile applications — especially agriculture, material processing and construction.

The present invention has a unique market position in this field, allowing full control of gear set manufacture while providing higher performance and individualized design for hydraulic motors, smoother motor operation, higher efficiency (and more consistent efficiency over the life of the motor), better life expectancy of the motor and rollers, particularly in applications with many start/stop/reverse rotations.

Drawings

Fig. 1 is a schematic structural diagram of a hydraulic motor according to an embodiment of the present invention.

Fig. 2 is a sectional structural view of a hydraulic motor according to an embodiment of the present invention.

Fig. 3 is a working schematic diagram of a hydraulic motor according to an embodiment of the present invention.

Fig. 4 is an assembly view of a hydraulic motor provided in an embodiment of the present invention.

Fig. 5 is an external view of a hydraulic motor according to an embodiment of the present invention.

Fig. 6 is an external view of a hydraulic motor according to an embodiment of the present invention.

Detailed Description

In order to further understand the contents, features and effects of the present invention, the following embodiments are illustrated and described in detail with reference to the accompanying drawings.

In order to solve the problems in the prior art, the present invention provides a hydraulic motor, which is described in detail below with reference to the accompanying drawings.

The hydraulic motor, also known as an internal gear motor, can achieve high speed-low torque and is a direct drive when no commutator is included, but is an indirect drive or orbital motor when a commutator is included. The rotating group consists of an inner rotor, an outer rotor and a roller. The inner rotor has one less tooth than the outer ring, is eccentric in center, and has eccentricity. The outer rotor and roller are stationary and the inner rotor rotates about the center of the outer portion as it is forced to rotate by the flow.

The inner rotor in the figure has 6 teeth and 7 rollers. The spaces between them are pressure chambers in which oil will be used to rotate the inner rotor. The diverter receives flow from the port and sends it to the manifold to supply the pressure chamber.

The standard design of the rollers used in prior art hydraulic motors is set to diameter 15.9825 (fig. 1), and the diameter of the roller of the present invention is set to a fairly unique dimension 16.0000 to control all other components of the gear (fig. 2). The phi 16 precision roll is used for the pinch point, providing more power and longer service life. Each output shaft is custom ground to maintain precise tolerances between the housing and the shaft, resulting in high volumetric efficiency.

The hydraulic energy (flow/pressure) is converted into mechanical energy through the gear set, the universal shaft and the output shaft when the motor works. The gear set consists of two parts, namely an outer edge (roller) and an inner gear, wherein the outer edge (roller) is a component of the shell of the motor, and the inner gear rotates in the rim and rotates around the center. The cardan shaft transfers torque from the gear shaft to the output shaft, which allows the cardan shaft centerline to rotate in the presence of gear set eccentricity. The output shaft transmits torque to the application. The output shaft and bearings are also subjected to radial loads.

Valves are required to meter flow into and out of the gear chambers during operation, and spool and disk valves are used with the hydraulic motors used. The spool valve is integrated in the shaft, which therefore has two purposes: transmitting torque and rotating the valve; the design makes the motor compact and the rotating parts are few. The disc valve distributor valve is separated from the output shaft and driven by a separate cardan shaft; the balance plate balances the forces around the distribution valve, minimizing volume and mechanical losses. This design allows precise valve function with high volumetric efficiency at any pressure.

While the principles, embodiments and operations of the present invention have been illustrated and described in detail herein, the drawings and this description are not to be construed as limited to the particular illustrative forms disclosed. It will therefore be apparent to those skilled in the art that various modifications can be made in the embodiments herein without departing from the spirit or scope of the invention. Referring now in more detail to fig. 1, a slitter hydraulic motor 10 includes an end plate 11, a manifold 12, a drive assembly 13, a wear plate 14, a housing 15, an output assembly 16, and a longitudinal axis 17. As described further below, the

members

11, 12, 13, 14, 15, and 16 are each generally cylindrical and are shown in fig. 1 as separate components. Alternatively, some of these components may be integral with one another. Also, the hydraulic motor 10 may be a separate structure from the other hydraulic components in the hydraulic circuit, or it may be integral with and in a common housing with the other components in the hydraulic circuit, or may be bolted to such other components. In the presently preferred embodiment of the hydraulic motor 10, and as shown in FIG. 2 below, the hydraulic motor 10 is bolted to the hydraulic pump 98 in a well known manner. When the hydraulic motor 10 and hydraulic pump 98 are bolted together or in an integral housing and used to propel a vehicle, as described below with reference to FIG. 2, the motor and pump assembly is sometimes referred to as a combined hydraulic transmission. As also explained in further detail below, the hydraulic motor 10 is driven in a rotational direction about its longitudinal axis 17 in a forward or reverse direction by pressurized fluid from a hydraulic pump. In the embodiment shown here, the hydraulic motor 10 is arranged such that its forward direction is counterclockwise when viewed in the longitudinal direction from the right end to the left end thereof in fig. 1. When the terms counterclockwise and clockwise are used herein, reference is made to the motor 10 being viewed in that direction. The reverse direction of the motor 10 is clockwise. During most of the operation of the motor 10, it is operating in the forward direction, and the reverse direction is generally used less frequently. The operation of the hydraulic motor 10 is described below in the forward direction, and as is well known, the reverse rotational direction of the motor 10 may be achieved by reversing the flow of hydraulic fluid through the motor 10. The end plate 11 of the hydraulic motor includes a plurality of inlet plate bolt holes 20, only one of which is shown in fig. 1. Each bolt hole 20 receives a bolt 21. Bolts 21 secure inlet plate 11, manifold 12, drive assembly 13, wear plate 14 and housing 15 together in a well known manner. In the preferred embodiment, the end plate 11 is preferably forged from steel, but alternatively may be cast or have any other suitable construction in a well known manner.

As shown in fig. 1, the manifold 12 includes a generally planar diverter plate 22 and generally planar retaining plates 23-28. A diverter plate 22 separates the inlet chamber 18 from the outlet chamber 19. The stationary plates 23-28 each include a plurality of

fluid flow passages

29 and 33 that extend through the stationary plates 23-28. The fluid flow passages 29 terminate at passage openings 29a-29g at a transverse or radial end face 32 of the stator plate 28, as described further below. Plates 23-28 also each include seven bolt holes 30 for receiving bolts 21 and for providing a fluid flow path.

The retaining plates 23-28 of the manifold 12 are steel plates brazed together in a well-known manner. The diverter plate 22 is driven by a drive link 31 of the output assembly 16, as described further below. The diverter plate 22 is moved in an orbital path relative to the fixed plates 23-28 by drive links 31 in a known manner to open and close fluid communication between the inlet chamber 18 and the channel 29 and between the outlet chamber 19 and the channel 29. The passage 29 of the manifold 12, in turn, supplies high pressure pressurized hydraulic fluid from the inlet chamber 18 to the drive assembly 13 and receives low pressure return hydraulic fluid from the drive assembly 13 to cause the hydraulic motor 10 to rotate in the forward direction. As also described further below. The longitudinally facing planar lateral end faces 32 of the manifold plates 28 of the manifold 12 are disposed in a plane perpendicular to the axis 17.

The drive assembly 13 includes a stator 36 and a rotor 37. The stator 36 and the rotor 37 each comprise a planar lateral end face 38, the lateral end face 38 being disposed in a plane parallel to the end face 32 and engaging the end face 32. Stator 36 and rotor 37 also include another planar lateral end face 39, which lateral end face 39 is parallel to end face 38 and engages wear plate 14.

The stator 36 includes seven bolt holes 40, only one of which is shown in fig. 1, for receiving the bolts 21 and for providing a fluid flow passage. The stator 36 also includes a central opening 41 extending longitudinally along the longitudinal axis 17. The transverse cross-section of the central opening 41 is generally circular. As described further below, the opening 41 provides seven semi-circular longitudinally extending pockets 42, each pocket 42 receiving a longitudinally extending cylindrical roller 43, the cylindrical rollers 43 being free to rotate in their respective pockets. Each roller 43 includes a cylindrical surface 48 and end faces 49 and 50 as shown in fig. 1. The seven rollers 43 provide seven internal gear teeth within the central opening 41, the seven internal gear teeth 43 providing an internal gear set for the drive assembly 13.

The above description is only for the preferred embodiment of the present invention, and is not intended to limit the present invention in any way, and all simple modifications, equivalent changes and modifications made to the above embodiment according to the technical spirit of the present invention are within the scope of the technical solution of the present invention.

Claims

1. A precision hydraulic roll comprising a drive assembly including a stator and a rotor, each of the stator and the rotor having a longitudinal axis; wherein at least one of said stator and said rotor comprises a plurality of rollers, each said roller having a rounded outer surface and an end surface, said rounded surface of said roller defining a first set of teeth that mesh with a second set of teeth on the other of said stator and said rotor, said first and second sets of teeth defining expanding and contracting fluid chambers;

2. The precision hydraulic roll of claim 1, wherein the stator comprises a plurality of roll cavities, each of the rolls is disposed in one of the roll cavities and provides the first set of teeth, and the rotor has a surface defining a second set of teeth.

3. The precision hydraulic roll of claim 1, wherein the longitudinal axes of the rotor and the stator are parallel and spaced apart.

4. A precision hydraulic roll as set forth in claim 1 further comprising a plurality of fluid passages and each of said plurality of fluid passages extending between one of said fluid chambers and one of said roll end faces and establishing fluid pressure communication.

5. The precision hydraulic roller as recited in claim 4 wherein the number of fluid channels is the same as the number of rollers and chambers.

6. A precision hydraulic roll as claimed in claim 1 further comprising a member adjacent to the rotor and stator, said fluid channels being at least partially located within said member, said member and said rotor and said stator each comprising radial end faces, all of said end faces lying in a plane, and all of said planes being parallel.

7. A precision hydraulic roll as set forth in claim 1 wherein each of said rolls includes another end surface, another fluid passageway extending between said fluid chamber and said first-mentioned roll end surface and establishing fluid pressure communication.

8. The precision hydraulic roll of claim 7 including a plurality of first fluid passages, each first fluid passage extending between and establishing fluid pressure communication between one of said fluid chambers and said first roll end face, each fluid passage having a second fluid passage extending between and establishing fluid pressure communication between one of said fluid chambers and one of said other roll end faces.

9. The precision hydraulic roll of claim 8, wherein the first fluid channel and the second fluid channel are equal in number to the roll.

10. The precision hydraulic roll of claim 9, wherein said first set of teeth and said second set of teeth are operatively engaged along a line of contact separating each of said fluid chambers from each other and said fluid chambers are one on each, said pressure level of each said line of contact being higher than the other side of said line of contact.

11. The precision hydraulic roll of claim 8, wherein each of said first fluid passages establishes substantially open hydraulic communication between a higher pressure level fluid chamber adjacent each said contact line and an end face of the first-mentioned roll defining said contact line, and each of said second fluid passages establishes fluid pressure communication between a higher pressure level fluid chamber adjacent each said contact line and said other end face of the roll defining said contact line.

12. The precision hydraulic roll of claim 11 comprising a first member comprising a surface adjacent to the rotor and the stator and the roll, a second member comprising another surface adjacent to the rotor, the stator and the roll; the fluid channel is at least partially within the first member and the other fluid channel is at least partially within the second member.

13. The precision hydraulic roll of claim 12 wherein the stator and the rotor and the first member each comprise a radial end face, the radial end faces of the stator, the rotor and the first member, and the first-mentioned end face of the roll are all parallel, the stator and the rotor and the second member each comprise another radial end face, and the stator, the rotor, the other radial end faces of the second member, and the another end face of the roll are all parallel.

14. The precision hydraulic roll of claim 12, wherein the first fluid channel is at least partially defined by the radial end face of the first member and the second fluid channel is at least partially defined by the radial end face of the second member.

15. The precision hydraulic roll of claim 8, wherein the first fluid channel is defined by a groove in the radial end face of the first member and the second fluid channel is defined by a groove in the radial end face of the second member.

16. A hydraulic motor incorporating a precision hydraulic roller as claimed in any one of claims 1 to 15, comprising a drive assembly, a manifold and wear plate:

17. A hydraulic motor according to claim 16, wherein each of the manifold and the wear plate has at least one of the fluid passages.

18. A hydraulic motor according to claim 17, wherein the number of fluid passages in each of the manifolds and the wear plates and the rollers is the same, each of the fluid passages in the manifolds establishing fluid pressure communication between one end face of one of the rollers and one fluid chamber adjacent the roller, and each of the fluid passages in the wear plates establishing fluid pressure communication between the other end face of one of the rollers and the fluid chamber adjacent the roller.

19. A hydraulic motor according to claim 18, wherein the fluid passages in the manifold and the wear plate in fluid communication with the first and second end faces of each respective roller are in fluid communication with the same fluid chamber fluid pressure.

20. A hydraulic motor according to claim 19, wherein each of the channels in the wear plates is in fluid communication with the one end face of one and only one of the rollers, and each of the channels in the manifold is in fluid communication with the other end face of one and only one of the rollers.

21. A hydraulic motor as claimed in claim 16, wherein the motor is assembled in a hydraulic circuit comprising a variable displacement hydraulic pump, the pump including an output control mechanism for manual hold and operation by operator input; the hydraulic pump operates at a pressure level greater than 1000 psi, the hydraulic pump has a fluid pressure outlet hydraulically connected to the electric motor, and the electric motor operates at a speed of less than five revolutions per minute.

22. A low-speed high-torque hydraulic system equipped with the precision hydraulic roll of any one of claims 1 to 15, comprising:

a drive, manifold, wear plate and housing:

23. The low speed, high torque hydraulic system of claim 22, wherein the number of fluid chambers, the number of rollers, the number of fluid passages in the wear plate, and the number of fluid passages in the manifold are the same.

24. The low speed, high torque hydraulic system of claim 23, wherein the fluid passages in the wear plate and manifold in communication with the first and second end faces of each of the rollers are open and closed to fluid communication at the same time for the same fluid chamber.