US20240410282A1

US20240410282A1 - Hydraulic machine with a threaded central pin for setting machine preload

Info

Publication number: US20240410282A1
Application number: US18/332,362
Authority: US
Inventors: Luca Fontanesi; Piergiorgio Trinchieri; Fabio NATALI
Original assignee: Dana Motion Systems Italia SRL
Current assignee: Dana Motion Systems Italia SRL
Priority date: 2023-06-09
Filing date: 2023-06-09
Publication date: 2024-12-12
Also published as: DE202024103026U1

Abstract

Systems and methods for a hydraulic machine. The hydraulic machine includes, in one example, a rotational shaft, a central pin rotationally coupled to the rotational shaft and threadingly engaged with a cylinder block via a threaded interface, and pistons coupled to the rotational shaft and mated with cylinders in the cylinder block. The hydraulic machine further includes a distribution plate in fluidic communication with the cylinders and a fluid inlet and a fluid outlet.

Description

TECHNICAL FIELD

The present disclosure relates to a hydraulic machine with a central pin that is configured to set a preload in the machine.

BACKGROUND AND SUMMARY

Previous hydraulic machines, such as hydraulic motors and pumps, have included a drive shaft connected to a cylinder block which interacts pistons. The pistons reciprocate in the cylinder block to generate fluid flow. Certain hydraulic machines, such as axial piston pumps and motors, have included spring loaded pins.
The inventors have recognized several issues with hydraulic pumps and motors that use spring loaded pins. For instance, during an overpressure condition in the machine, a cylinder block may separate from a distributor, causing oil to leak from the interface between the block and the distributor, in some instances. Consequently, pump efficiency is decreased and machine degradation may occur, in some cases.
Facing the abovementioned issues, the inventors developed a hydraulic machine to at least partially overcome the issues. The hydraulic machine includes, in one example, a rotational shaft and a central pin that is rotationally coupled to the rotational shaft and threadingly engaged with a cylinder block via a threaded interface. The hydraulic machine further includes multiple pistons which are coupled to the rotational shaft and mated with multiple cylinders in the cylinder block and a distribution plate that is in fluidic communication with the cylinders and a fluid inlet and a fluid outlet. In this way, a clearance between the cylinder block and the distribution plate may be precisely set by adjusting the threaded interface formed between the central threaded pin and threads in the cylinder block. Consequently, the chance of fluid leakage (caused by overpressure conditions) at the interface between the cylinder block and the distribution plate is reduced. To elaborate, the use of the threaded central pin reduces the chance of the distributor plate undesirably separating from the cylinder block. Further, the mechanical efficiency of the machine may be increased due to a reduction in friction between the cylinder block and the distribution plate, if desired.
Further, in one example, the hydraulic machine may include a threaded retainer ring positioned in the cylinder block and axially delimiting the central pin. Still further in one example, the machine may additionally include a tailstock pin threadingly engaged with the distribution plate and mated with a central recess in the cylinder block. The threaded retainer ring allows the position of the central piston to be set with regard to the cylinder block after the targeted amount of preload is set. Consequently, the likelihood of an undesirable separation between the cylinder block and the distribution plate which may lead to fluid leakage, machine inefficiency, and operational degradation is further reduced.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows a schematic depiction of a hydraulic system with a hydraulic machine.

FIG. 2 shows an example of a hydraulic machine with a threaded central pin.

FIG. 3 shows a cross-sectional view of the hydraulic machine, depicted in FIG. 2 .

FIG. 4 shows a detailed view of a distribution plate of the hydraulic machine, depicted in FIG. 2 .

DETAILED DESCRIPTION

A hydraulic machine, such as a hydraulic motor or pump, that achieves a targeted amount of preload in the machine assembly is described herein. To achieve the targeted preload, a central pin is threaded into the cylinder block and the amount of threaded engagement between the pin and the block dictates the amount of clearance between the cylinder block and a distribution plate which is sealingly engaged with the block. In this way, the amount of sealing and friction between the cylinder block and the distribution plate is able to be precisely balanced to achieve greater machine efficiency while maintaining sealing functionality (even in the event of an overpressure condition), if desired. The threaded pin allows a spring to be omitted from the hydraulic machine, if desired. Consequently, the construction of the hydraulic machine may be simplified, if desired. Further, using the threaded central pin to set the machine's preload decreases the chance of the cylinder block detaching from the distribution plate which decreases machine efficiency and may cause operational degradation due to fluid leakage when compared to previous hydraulic machines.
FIG. 1 shows a hydraulic machine 100 (e.g., a hydraulic motor, a hydraulic pump, and the like) in a system 102 (e.g., a drilling machine). In one example, the hydraulic machine 100 may be deployed in a hydrostatic transmission 104. However, the hydraulic machine 100 may be used in other suitable operating environments, in alternate examples.
The hydrostatic transmission 104 may include another hydraulic machine 106 that is in fluidic communication with ports 108 and 110 (e.g., an inlet port and an outlet port) of the hydraulic machine 100 via hydraulic lines 112 and 114, respectively. The hydraulic machine 100 is rotationally connected to a device 116 via a shaft 117 and/or other suitable rotational mechanical connection. The device 116 may be a drill device (e.g., a drill head), in one specific example. The hydraulic machine 106 is rotationally coupled to a device 118 via a shaft 119 and/or other suitable rotational mechanical connection. The device 118 may be a prime mover such as an engine or an electric motor, in different examples. Conversely, the device 116 may be a prime mover and the device 118 may be a drill device, in alternate examples. In either case, hydraulic fluid (e.g., oil) is circulated between the hydraulic machine 100 and the hydraulic machine 106 to allow for power to be hydraulically transferred between the machines. The fluid may flow clockwise or counterclockwise through the lines 112, 114 in the frame of reference of FIG. 1 . As such, the hydraulic machine 100 may be a hydraulic motor and the hydraulic machine 106 may be a hydraulic pump or vice versa.
The system 102 may further include a controller 190. The controller 190 may include a microcomputer with components such as a processor 192 (e.g., a microprocessor unit), input/output ports, an electronic storage medium 194 for executable programs and calibration values (e.g., a read-only memory chip, random access memory, keep alive memory, a data bus, and the like). The storage medium may be programmed with computer readable data representing instructions that are executable by the processor for performing the methods and control techniques described herein as well as other variants that are anticipated but not specifically listed. As such, control techniques, methods, and the like expanded upon herein may be stored as instructions in non-transitory memory.
The controller 190 may receive various signals from sensors 195 coupled to various regions of the system 102. For example, the sensors 195 may include hydraulic unit pressure sensors, hydraulic unit speed sensors, temperature sensors, and the like. An input device 198 may further provide input signals indicative of an operator's intent for system control.
Upon receiving the signals from the various sensors 195 of FIG. 1 , the controller 190 processes the received signals, and employs various actuators 196 of system components to adjust the components based on the received signals and instructions stored on the memory of controller 190. For example, the controller 190 may be designed to alter the speed of the device 118 (e.g., prime mover) be sending a control command to an actuator in the prime mover which in response adjusts prime mover output speed. The other controllable components in the system may function in a similar manner with regard to sensor signals, control commands, and actuator adjustment, for example.
An axis system is provided in FIG. 1 as well as FIGS. 2-4 , for reference. The z-axis may be a vertical axis (e.g., parallel to a gravitational axis), the x-axis may be a lateral axis (e.g., horizontal axis), and/or the y-axis may be a longitudinal axis, in one example. However, the axes may have other orientations, in other examples.
FIG. 2 shows an example of a hydraulic machine 200. The hydraulic machine 200 may be included in the hydrostatic transmission 104 shown in FIG. 1 or another suitable hydrostatic transmission or system. Therefore, the hydraulic machine 200 shown in FIG. 2 may include at least some overlapping structural and functional features with the hydraulic machine 100 depicted in FIG. 1 and vice versa.
The hydraulic machine 200 is illustrated as an axial piston machine. To elaborate, the hydraulic machine 200 may be a bent axis hydraulic machine. For instance, the hydraulic machine 200 may be a bent axis hydraulic motor, in one example, or a bent axis hydraulic pump, in another example.
The hydraulic machine 200 includes a shaft 300, shown in FIG. 3 , which may be surrounded by a housing 203, shown in FIG. 2 . An angle 302 is formed between a rotational axis 304 of the shaft 300 and a rotational axis 306 of a cylinder block 202, as illustrated in FIG. 3 . The angle may be less than 40°, in one specific use-case example. However, a variety of angles are possible. Bent axis hydraulic machines may have a wider operating torque/speed range than other hydraulic machines such as inline machines.
The housing 203 includes a section 205 that may at least partially surround the shaft 300, shown in FIG. 3 , the cylinder block 202, and a central pin 204. Continuing with FIG. 2 , another housing section may be coupled to the housing section 205 via attachment devices 207.
The hydraulic machine 200 further includes a central pin 204, the cylinder block 202, and a distribution plate 206. The central pin 204 is coupled to the shaft 300, shown in FIG. 3 , and the cylinder block 202 when assembled. The threaded engagement between threads on the central pin 204 and threads in the cylinder block 202 dictates the preload applied to the distribution plate 206 and therefore a clearance between the distribution plate 206 and the cylinder block 202. Preloading the block to affect the clearance is expanded upon herein.
The central pin 204 includes a threaded section 208 which may extend to one end 210 of the pin. The central pin 204 may further include a male joint section 212 (e.g., spherical joint section) at another end 214. The male joint section 212 is profiled to mate with a female joint section 308 in the shaft 300, shown in FIG. 3 . The rotational joint (e.g., ball joint) formed between the pin and the shaft is described in greater detail herein.
The hydraulic machine 200 may further include a retainer ring 216 which may be profiled to thread into the cylinder block 202 and axially delimit the central pin. The hydraulic machine 200 may further include a sealing assembly 218 which may include a seal 220 and a seal 222. The seal 220 may be a metal ring seal and the seal 222 may be a wave spring. However, other sealing assembly arrangements have been contemplated. The sealing assembly 218 is configured to reduce the chance of fluid leakage between the cylinder block 202 and the distribution plate 206. Thus, the seals 220, 222 may be in face sharing contact with the block and the plate when the machine is assembled. Further, the seals 220, 222 may be positioned radially outward from cylinders 224 formed in the cylinder block 202. The cylinders 224 receive pistons which reciprocate therein, during machine operation.
The hydraulic machine 200 may further include a tailstock pin 226. The tailstock pin 226 may include a section 227 (e.g., an unthreaded section) profiled to mate with an opening 228 in the cylinder block 202 and abut the central pin 204, when assembled. Further, the tailstock pin 226 may include a threaded section 230 that is profiled to theadingly engage a central opening 232 in the distribution plate 206 which is threaded. The tailstock pin 226 may further include a flange 234 and a head 236, in some examples.
FIG. 3 shows a cross-sectional view of the hydraulic machine 200. The cutting plane for the view extends through the rotational axis 304 of the shaft 300.
The shaft 300, the central pin 204, and the distribution plate 206 are shown in FIG. 3 along with the tailstock pin 226, and the housing 203. The housing 203 may at least partially surround the shaft 300, the cylinder block 202, and the distribution plate 206, as previously indicated.
The hydraulic machine 200 includes pistons 310 that are pivotally coupled to the shaft 300 via rotational joints (e.g., ball joints). The pistons 310 each include a male joint section 312 (e.g., a spherical joint section) that are profiled to mate with a female joint section 314 in the shaft 300. The pistons 310 mate with the cylinders 224 and reciprocate therein during machine operation. Piston rings 316 may be mated with the pistons to reduce the chance of fluid leakage. The cylinders 224 each include a fluid port 318 that act as a fluid inlet and a fluid outlet during machine operation. The position of the cylinders with regard to the distribution plate dictate the direction of fluid flow through the fluid ports.
A threaded interface 320 between the central pin 204 and the cylinder block 202 is depicted. The threaded interface 320 includes threads 322 in the central pin 204 and threads 324 in the cylinder block 202. The threaded connection between the cylinder block 202 and the central pin 204 forms a more rigid connection between the components when compared to an elastic connection in other machines that is formed with a spring. This rigid connection increases mechanical performance of the machine while reducing the chance of fluid leakage. Further, it will be appreciated that a spring which is coupled to the central pin may be omitted from the machine.
A clearance 326 between the distribution plate 206 and the cylinder block 202 is further depicted in FIG. 2 . During machine set-up, the amount of clearance may be set by adjusting the amount of threaded engagement between the central pin 204 and the cylinder block 202. To elaborate, an end face 328 of the central pin 204 abuts an end face 330 (shown in FIG. 2 ) of the tailstock pin 226. As such, when the central pin 204 is further threaded into the cylinder block 202 the amount of clearance is increased and vice versa. In this way, the amount of clearance is able to be precisely tailored to increase machine performance and efficiency. Further, due to the rigid connection established between the central pin 204 and the cylinder block 202 the clearance 326, depicted in FIG. 3 , which is adjusted during set-up may remain substantially constant throughout machine operation and detachment of the distribution plate from the cylinder block caused by overpressure conditions can be avoided. Further, the threaded engagement between the central pin 204 and the cylinder block 202 allows cylinder block stroke to be adjusted without machine disassembly or the use of a measuring tool, if desired. Further, the assembly process may be simplified by using a threaded connection between the central pin 204 and the cylinder block 202. For instance, checking an end screw slide to determine that a desirable clearance is achieved may be avoided during the assembly process, if so desired.
The retainer ring 216 which axially delimits the central pin 204 is further depicted in FIG. 3 . The seals 220, 222 are further depicted in FIG. 3 along with another seal 332 that may be included in the sealing assembly 218. The seals 220, 222 are positioned radially outward from the cylinders 224 and the seal 332 is positioned radially inward from the cylinders, in the illustrated example. In this way, the cylinders are reliably sealed. However, other sealing arrangements have been contemplated.
The shaft 300 is configured to rotationally attach to a device 334 which may transfer rotational energy to the shaft or vice versa, in different examples. For instance, the device may be a prime mover such as an engine or electric motor or a drill device, in different use-case examples.
The tailstock pin 226 is shown forming a threaded interface 336 with the distribution plate 206 in FIG. 3 . Further, a portion of the tailstock pin 226 mates with the opening 228 in the cylinder block 202 which allows the tailstock pin 226 to abut the central pin 204.
A bearing 338 and/or a bearing 340 may be coupled to the shaft 300. The bearings 338, 340 may be tapered roller bearings, in one example, to manage axial and radial loading. However, other types of bearings may be used in other examples, such as roller bearings, ball bearings, and the like.
The distribution plate 206 includes fluid ports 342 and fluid ports 344 that may be in fluidic communication with ports 345 in another hydraulic machine 346 as previously discussed. For instance, when the machine 200 is a hydraulic motor the fluid ports 342 and the fluid ports 344 are hydraulically coupled to ports in a hydraulic pump and vice versa.
FIG. 4 shows a detailed view of the distribution plate 206. An inboard side 400 of the plate 206 is shown with fluid ports 342 and fluid ports 344. The fluid ports 342 may function as inlet ports and the fluid ports 344 may function as outlet ports or vice versa. The direction of machine rotate may dictate the direction of fluid flow through the fluid ports in the distribution plate. The central opening 232 is further depicted in FIG. 4 . A surface 402, which may be curved, of the inboard side 400 is further shown in FIG. 4 .
FIGS. 1-4 provide for a method for operation of a hydraulic machine. The method may be carried out by any of the hydraulic machines or combinations of the hydraulic machines described herein with regard to FIGS. 1-4 , in one example. In other examples, the method may be implemented by other suitable hydraulic machines. Furthermore, the method may be implemented by a controller that includes memory holding instructions for the method steps that are executable by a processor, as previously indicated. The method includes rotating the machine's shaft while a preload force is exerted on the distribution plate via a central pin. Shaft rotation may be induced by a prime mover, in one example, or by hydraulic flow through the machine, in another example. The method may therefore further include circulating fluid between another hydraulic machine and the first hydraulic machine. In this step, fluid flows from the second hydraulic machine to the first hydraulic machine and vice versa.
The technical effect of the hydraulic machine operating methods described herein is to increase machine performance while reducing the chance of fluid leakage from the machine.
FIGS. 1-4 show example configurations with relative positioning of the various components. If shown directly contacting each other, or directly coupled, then such elements may be referred to as directly contacting or directly coupled, respectively, at least in one example. Similarly, elements shown contiguous or adjacent to one another may be contiguous or adjacent to each other, respectively, at least in one example. As an example, components laying in face-sharing contact with each other may be referred to as in face-sharing contact. As another example, elements positioned apart from each other with only a space there-between and no other components may be referred to as such, in at least one example. As yet another example, elements shown above/below one another, at opposite sides to one another, or to the left/right of one another may be referred to as such, relative to one another. Further, as shown in the figures, a topmost element or point of element may be referred to as a “top” of the component and a bottommost element or point of the element may be referred to as a “bottom” of the component, in at least one example. As used herein, top/bottom, upper/lower, above/below, may be relative to a vertical axis of the figures and used to describe positioning of elements of the figures relative to one another. As such, elements shown above other elements are positioned vertically above the other elements, in one example. As yet another example, shapes of the elements depicted within the figures may be referred to as having those shapes (e.g., such as being circular, straight, planar, curved, rounded, chamfered, angled, or the like). Additionally, elements co-axial with one another may be referred to as such, in one example. Further, elements shown intersecting one another may be referred to as intersecting elements or intersecting one another, in at least one example. Further still, an element shown within another element or shown outside of another element may be referred as such, in one example. In other examples, elements offset from one another may be referred to as such. Even further, elements which are coaxial or parallel to one another may be referred to as such. Still further, an axis about which a component rotates may be referred to as a rotational axis.
The invention will be further described in the following paragraphs. In one aspect, a hydraulic machine is provided that comprises a rotational shaft; a central pin rotationally coupled to the rotational shaft and threadingly engaged with a cylinder block via a threaded interface; a plurality of pistons coupled to the rotational shaft and mated with a plurality of cylinders in the cylinder block; and a distribution plate in fluidic communication with the plurality of cylinders and a fluid inlet and a fluid outlet. Further in one example, the hydraulic machine may further comprise a threaded retainer ring positioned in the cylinder block and axially delimiting the central pin. Further in one example, the hydraulic machine may further comprise a tailstock pin threadingly engaged with the distribution plate and mated with a central recess in the cylinder block. Further in one example, the hydraulic machine may further comprise a seal formed between the tailstock pin, the cylinder block, and the distribution plate. Further in one example, the hydraulic machine may further comprise a seal formed between the distribution plate and the cylinder block. Further in one example, the interface between the central pin and the cylinder block may not include a spring. Further in one example, the hydraulic machine may further comprise a bearing coupled to the rotational shaft and a housing. Still further in one example, the hydraulic machine may be a bent axis hydraulic motor. Still further in one example, the hydraulic motor may be included in a hydrostatic transmission.
In another aspect, a method for operation of a first hydraulic machine is provided that comprises rotating a rotational shaft while a preload force is exerted on a distribution plate by a cylinder block; wherein an amount of preload force is dictated by an amount of threaded engagement between a central pin and the cylinder block; wherein the hydraulic machine includes: the rotational shaft; the central pin rotationally coupled to the rotational shaft and threadingly engaged with the cylinder block; a plurality of pistons coupled to the rotational shaft and mated with a plurality of cylinders in the cylinder block; and the distribution plate in fluidic communication with the plurality of cylinders and a fluid inlet and a fluid outlet. Further, in one example, the method may further comprise flowing a fluid from the fluid outlet to a second hydraulic machine. Further, in one example, the second hydraulic machine may be a hydraulic pump. Still further, in one example, the hydraulic pump may be included in a hydrostatic transmission.
In yet another aspect, a bent axis hydraulic machine is provided that comprises a rotational shaft; a central pin rotationally coupled to the rotational shaft and threadingly engaged with a cylinder block; a plurality of pistons coupled to the rotational shaft and mated with a plurality of cylinders in the cylinder block; and a distribution plate in fluidic communication with the plurality of cylinders and a fluid inlet and a fluid outlet; wherein the cylinder block exerts a preload force on the distribution plate that is based on an amount of threaded engagement between the central pin and the cylinder block. Further, in one example, the hydraulic machine may further comprise a tailstock pin threadingly engaged with the distribution plate, mated with a central recess in the cylinder block, and in face sharing contact with an end of the central pin. Further, in one example, the hydraulic machine may further comprise a sealing assembly configured to seal the cylinder block and the distribution plate. Still further in one example, the sealing assembly may include a first seal which is arranged between the cylinder block and the distribution plate and positioned radially outward from the fluid inlet and the fluid outlet. Further in one example, the sealing assembly may include a second seal which is arranged between the cylinder block, the distribution plate, and a tailstock pin threadingly engaged with the distribution plate, mated with a central recess in the cylinder block. Still further in one example, the bent axis hydraulic machine may be a bent axis motor that is in fluidic communication with a hydraulic pump. Further in one example, the central pin may not include a spring positioned therein or directly coupled thereto.
In another representation, a hydrostatic machine is provided that comprises an inner pin that pivotally attaches to a rotational shaft at a first end and threads into a cylinder block at a second end to set preload exerted on a distribution plate.
Note that the example control and estimation routines included herein can be used with various system (e.g., transmission) configurations. The control methods and routines disclosed herein may be stored as executable instructions in non-transitory memory and may be carried out by the control system including the controller in combination with the various sensors, actuators, and other system hardware in combination with the electronic controller. As such, the described actions, operations, and/or functions may graphically represent code to be programmed into non-transitory memory of the computer readable storage medium in the control system. The various actions, operations, and/or functions illustrated may be performed in the sequence illustrated, in parallel, or in some cases omitted. Likewise, the order of processing is not necessarily required to achieve the features and advantages of the examples described herein, but is provided for ease of illustration and description. One or more of the illustrated actions, operations and/or functions may be repeatedly performed depending on the particular strategy being used. One or more of the method steps described herein may be omitted if desired.
While various embodiments have been described above, it should be understood that they have been presented by way of example, and not limitation. It will be apparent to persons skilled in the relevant arts that the disclosed subject matter may be embodied in other specific forms without departing from the spirit of the subject matter. The embodiments described above are therefore to be considered in all respects as illustrative, not restrictive. As such, the configurations and routines disclosed herein are exemplary in nature, and that these specific examples are not to be considered in a limiting sense, because numerous variations are possible. For example, the above technology can be applied to systems (e.g., machinery, vehicles, and the like) that include different types of propulsion sources including different types of motors, internal combustion engines, transmissions, and the like. The subject matter of the present disclosure includes all novel and non-obvious combinations and sub-combinations of the various systems and configurations, and other features, functions, and/or properties disclosed herein.
The following claims particularly point out certain combinations and sub-combinations regarded as novel and non-obvious. These claims may refer to “an” element or “a first” element or the equivalent thereof. Such claims should be understood to include incorporation of one or more such elements, neither requiring nor excluding two or more such elements. Other combinations and sub-combinations of the disclosed features, functions, elements, and/or properties may be claimed through amendment of the present claims or through presentation of new claims in this or a related application. Such claims, whether broader, narrower, equal, or different in scope to the original claims, also are regarded as included within the subject matter of the present disclosure.

Claims

1. A hydraulic machine, comprising:

a rotational shaft;

a central pin rotationally coupled to the rotational shaft and threadingly engaged with a cylinder block via a threaded interface;

a plurality of pistons coupled to the rotational shaft and mated with a plurality of cylinders in the cylinder block; and

a distribution plate in fluidic communication with the plurality of cylinders and a fluid inlet and a fluid outlet.

2. The hydraulic machine of claim 1, further comprising a threaded retainer ring positioned in the cylinder block and axially delimiting the central pin.

3. The hydraulic machine of claim 1, further comprising a tailstock pin threadingly engaged with the distribution plate and mated with a central recess in the cylinder block.

4. The hydraulic machine of claim 3, further comprising a seal formed between the tailstock pin, the cylinder block, and the distribution plate.

5. The hydraulic machine of claim 1, further comprising a seal formed between the distribution plate and the cylinder block.

6. The hydraulic machine of claim 1, wherein an interface between the central pin and the cylinder block does not include a spring.

7. The hydraulic machine of claim 1, further comprising a bearing coupled to the rotational shaft and a housing.

8. The hydraulic machine of claim 1, wherein the hydraulic machine is a bent axis hydraulic motor.

9. The hydraulic machine of claim 8, wherein the bend axis hydraulic motor is included in a hydrostatic transmission.

10. A method for operation of a first hydraulic machine, comprising:

rotating a rotational shaft while a preload force is exerted on a distribution plate by a cylinder block;

wherein an amount of preload force is dictated by an amount of threaded engagement between a central pin and the cylinder block; and

wherein the first hydraulic machine includes:

the rotational shaft;

the central pin rotationally coupled to the rotational shaft and threadingly engaged with the cylinder block;

the distribution plate in fluidic communication with the plurality of cylinders and a fluid inlet and a fluid outlet.

11. The method of claim 10, further comprising flowing a fluid from the fluid outlet to a second hydraulic machine.

12. The method of claim 11, wherein the second hydraulic machine is a hydraulic pump.

13. The method of claim 12, wherein the hydraulic pump is included in a hydrostatic transmission.

14. A bent axis hydraulic machine, comprising:

a rotational shaft;

a central pin rotationally coupled to the rotational shaft and threadingly engaged with a cylinder block;

a distribution plate in fluidic communication with the plurality of cylinders and a fluid inlet and a fluid outlet;

wherein the cylinder block exerts a preload force on the distribution plate that is based on an amount of threaded engagement between the central pin and the cylinder block.

15. The bent axis hydraulic machine of claim 14, further comprising a tailstock pin threadingly engaged with the distribution plate, mated with a central recess in the cylinder block, and in face sharing contact with an end of the central pin.

16. The bent axis hydraulic machine of claim 14, further comprising a sealing assembly configured to seal the cylinder block and the distribution plate.

17. The bent axis hydraulic machine of claim 16, wherein the sealing assembly includes a first seal which is arranged between the cylinder block and the distribution plate and positioned radially outward from the fluid inlet and the fluid outlet.

18. The bent axis hydraulic machine of claim 17, wherein the sealing assembly includes a second seal which is arranged between the cylinder block, the distribution plate, and a tailstock pin threadingly engaged with the distribution plate, mated with a central recess in the cylinder block.

19. The bent axis hydraulic machine of claim 14, wherein the bent axis hydraulic machine is a bent axis motor that is in fluidic communication with a hydraulic pump.

20. The bent axis hydraulic machine of claim 14, wherein the central pin does not include a spring positioned therein or directly coupled thereto.