Abstract: The invention relates to a suspension for motor vehicles having controllable chassis clearance and stiffness, and includes a helical spring (1), having a controlling device (2) which is secured to the body of the vehicle and is located rotatably, preferably by means of a transmission stage driven by an electric motor. The controlling device (2) is embodied as a shaped nut, which is screwed directly onto the coils of the preferably cylindrical helical spring (1) and has roller bodies which are located along the helical line and are connected to coils of the helical spring; the controlling device (2) is fully movable and fixable onto and relative to the helical spring. The suspension for motor vehicles ensures enhanced stiffness of the suspension in the event of a decrease in the chassis clearance, reduced stiffness of the suspension when the chassis clearance is increased, and the possibility of building in a telescoping damper inside the helical spring without blocking access to its upper fastening point.

Abstract: An accumulator device (10) includes at least two accumulator elements (14, 16) that are combined to form a structural unit (12) and that have independently from one another their own accumulator characteristic curves (18, 20), in particular as a result of different preload pressures. The respective accumulator characteristic curves (18, 20) provide a combined total accumulator characteristic curve (22). A fluid can be stored in the structural unit (12) and can be retrieved from it. A hydropneumatic suspension system (24) has such an accumulator device (10).

Abstract: The present invention provides various devices and systems comprising a controller in connection with a first deployment mechanism to raise and lower a first lift axle on a wheeled vehicle, and in some cases a second deployment mechanism in connection with the controller for raising and lowering a second lift axle. A fail-safe mechanism is provided that automatically lowers the lift axle(s) if the controller is not receiving any electrical power.

Abstract: A pneumatic control system for a heavy-duty vehicle includes an air supply in fluid communication with a height control valve and an air spring. An air lock valve is in fluid communication with the height control valve and the air spring, and is also in fluid communication with a blank cavity. The air lock valve includes an “air lock off” position and an “air lock on” position. When the air lock valve is in the “air lock off” position, fluid flows from the height control valve, through the air lock valve to the air spring. When the air lock valve is in the “air lock on” position, fluid communication between the air spring, the air lock valve and the height control valve is prevented and, instead, fluid flows from the air spring, through the air lock valve to the blank cavity.

Abstract: A hydraulic actuator includes a shock absorber and a control system that is separate from the shock absorber and which generates damping loads for the hydraulic actuator. The control system generates the damping load by using a pair of variable valves, a pair of check valves, an accumulator, a pump/motor and a flow controller. The forces are generated in all four quadrants of compression/rebound and active/passive. A device which recuperates the energy generated by the hydraulic actuator can be incorporated into the hydraulic actuator to generate energy in the form of electrical energy.

Abstract: A crawler vehicle has a body and at least one left and one right track roller unit. The track roller units are connected to the body via a machine axis. The track roller units comprise a first and a second guide roller as well as a first and a second supporting arm on which the guide rollers are mounted. The first and the second supporting arms of each roller unit are mounted to be pivotable independently of one another about the machine axis.

Abstract: A bandpass filter is provided that prevents clock leakage to the input side of an amplifier circuit and has excellent out-of-passband signal attenuation. It includes an amplifier (102) connected between an input terminal and an output terminal, an impedance frequency conversion circuit (101) that is connected between an output of the amplifier and ground and changes impedance depending on whether or not the frequency of a signal output from the amplifier is within a predetermine passband, and a feedback circuit (103) connected between the output and an input of the amplifier.

Abstract: A spring for a suspension is described. The spring includes: a spring chamber divided into at least a primary portion and a secondary portion, and a fluid flow path coupled with and between the primary portion and the secondary portion. The fluid flow path includes a bypass mechanism, wherein the bypass mechanism is configured for automatically providing resistance within the fluid flow path in response to a compressed condition of the suspension.

Abstract: A gas spring for a vehicle suspension system includes a cylinder, a rod disposed within the cylinder, a relative movement between the rod and the cylinder changing the volume of a chamber formed between the rod and the cylinder, and an accumulator in communication with the chamber. Compression of gas in the chamber at least partially provides a first spring rate for deflections of the gas spring below a threshold, compression of gas in the chamber at least partially provides a second spring rate for deflections of the gas spring above the threshold, and the first spring rate is greater than the second spring rate.

Abstract: A spring constant of each of four suspension springs and a shared load on each of four wheels are adjusted so that a sprung resonance frequency corresponding to two front wheels and a sprung resonance frequency corresponding to two rear wheels are mutually different. From among the four shock absorbers, only two shock absorbers provided corresponding to two wheels of lowered sprung resonance frequency, from among the two front wheels and the two rear wheels have respectively damping coefficient modification mechanisms that modify a damping coefficient serving as a reference of the magnitude of the damping force generated by the two shock absorbers. The behavior of the entire vehicle body can be effectively curbed by controlling the damping force exerted on the comparatively large movement of sprung sections corresponding to the two wheels. Thus a vehicle having both enhanced steering stability and enhanced ride quality can be configured comparatively inexpensively.

Abstract: Methods and apparatus for regulating the function of a suspension system are disclosed herein. Suspension characteristics often contribute to the efficiency of a suspended system. Depending on the desired operating parameters of the suspended system, it may be desirable to alter the functional characteristics of the suspension from time to time in order to maintain or increase efficiency. The suspension hereof may be selectively locked into a substantially rigid configuration, and the damping fluid may be phase separated and/or cooled to increase damping rate during use (or offset rate degradation). The suspension hereof may generate power usable to achieve any or all of the foregoing or to be stored for use elsewhere in the suspended system or beyond.

Abstract: Disclosed is an improved snowmobile ski suspension including a pair of airspring biasing mechanisms whose air volumes are interconnected by a cross linking conduit that incorporates an open and closed switch. In an alternative embodiment a simpler configuration is provided for which does not include the use of an open or closed switch manifold.

Abstract: A method and apparatus for a vehicle shock absorber comprising a main damper cylinder, a first reservoir and a second reservoir. One embodiment includes a first operational mode where both reservoirs are in fluid communication with the cylinder. In a second operational mode, only one reservoir communicates with the cylinder during fluid evacuation from the cylinder. In each mode, rebound from either or both reservoirs may travel through a single, user-adjustable metering device.

Abstract: In a vehicle-height adjustment apparatus of a motorcycle having the hydraulic jack attached to the damper, damping force characteristics of a damper are stabilized, the influence of the charged gas pressure of an oil reservoir chamber is eliminated, and the sealing performance of a hydraulic jack is reduced. In the vehicle-height adjustment apparatus of a motorcycle, a back pressure chamber is provided on a side opposite to a jack chamber, with a plunger being interposed therebetween inside a hydraulic jack, and this back pressure chamber is communicated with a hydraulic chamber inside a damper tube.

Abstract: A shock absorber for a vehicle having a damper and a first and second springs mounted coaxially around the damper and a preload adjuster for partially compressing at least one of the springs independently of the compression stroke. In one embodiment the preload adjuster is remotely controllable. In another embodiment the shock absorber includes an additional mechanism for preloading at least one of the springs.

Abstract: A gas spring for a vehicle suspension system includes a cylinder, a rod, and an accumulator. The rod is disposed within the cylinder, and relative movement between the rod and the cylinder changes the volume of a chamber formed between the rod and the cylinder. The accumulator is in gaseous communication with the chamber such that a continuous body of gas extends between the chamber and the accumulator.

Abstract: The present disclosure relates to spare tire damper assemblies for a vehicle and methods for reducing vibration. The assemblies can include a support frame configured to secure a spare tire thereto and a first adjustable isolator positioned with respect to the support frame. A second isolator is positioned in series with the first isolator so that adjustment of the first isolator adjusts a static preload of the second isolator.

Abstract: A shock absorber includes a hydraulic compression stop. The hydraulic stop includes a pressure tube surrounding the pressure tube of the shock absorber and a piston in hydraulic communication with the interior of the pressure tube. The piston can be disposed within the pressure tube and can be attached to the pressure tube or to the shock absorber. The hydraulic stop can also include a hydraulic fluid chamber and the piston can be disposed within the hydraulic fluid chamber.

Abstract: A mounting bracket assembly, such as for securing a suspension component to a receiving element of sprung or unsprung mass of a vehicle, can include an internal mounting element. An external mounting element can be secured to the receiving element using a securement element. A suspension assembly for a vehicle and a method of assembly including such a mounting bracket assembly are also included. A mounting bracket kit is also included.

Abstract: An auxiliary axle suspension system for a motor vehicle is disclosed wherein a pair of hydraulically operated actuators position and force the auxiliary axle to help support the vehicle. And gas springs are provided that allow the actuators to extend and retract over a wide range of hydraulic operating pressure and thereby allow the auxiliary axle to adjust to a wide range of road grade differences between the auxiliary axle wheels and the wheels of the axles that normally support the vehicle without incurring significant gas and hydraulic pressure fluctuation and while isolating shock forces on the auxiliary axle wheels from the vehicle.

Abstract: A vehicle suspension system includes a pump, a gas spring, and an accumulator. The gas spring assembly includes a cylinder, a rod, and a chamber for supporting gas. The rod is coupled to the cylinder and moveable relative to the cylinder. The chamber is formed between the cylinder and the rod, where movement of the rod relative to the cylinder changes the volume of the chamber. The accumulator is configured for receiving, storing, and releasing potential energy from gas of the chamber. The accumulator is coupled to the chamber, and is in gaseous communication with the chamber such that a continuous body of gas extends between the chamber and the accumulator when the accumulator is receiving or releasing the potential energy.

Abstract: An analytical methodology for the specification of progressive optimal compression damping of a suspension system to negotiate severe events, yet provides very acceptable ride quality and handling during routine events. In a broad aspect, the method provides a progressive optimal unconstrained damping response of the wheel assembly with respect to the body. In a preferred aspect, the method provides a progressive optimal constrained damping response of the wheel assembly with respect to the body, wherein below a predetermined velocity a conventional damper force is retained.

Abstract: An air suspension system for a multi-axle vehicle having air bags (4,5; 6,7; 8,9; 10,11; 44 to 49) supporting either side of the axles (2,3; 41 to 43), including separate air lines (18 to 25; 50 to 55) respectively connecting each air bag to a level control valve (16,17; 56,57) via manifolds (26,27; M) and air lines (28,29; 54,55) to independently control air supply to the bags on either side, the separate air lines being of the same size and length to ensure that substantially the same volume of air is supplied to each bag to improve the responsiveness and stability of the system.

Abstract: Systems and methods for weight transfer in a vehicle are provided. One system includes a plurality of springs and a plurality of movable spring seats configured to adjust a length of the plurality of springs. Additionally, a pneumatic actuator is provided that is connected to the plurality of movable springs and configured to move the movable spring seats to adjust the length of the plurality of springs. Further, a controller is provided that is coupled to the pneumatic actuator to control the pneumatic actuator to adjust the length of the plurality of springs.

Abstract: An agricultural vehicle comprises separate wheel suspension assemblies corresponding to each wheel of the vehicle. Each wheel suspension assembly includes a strut assembly wherein the strut assembly is connected to the chassis at a pivot and to a respective wheel, and a dual action hydraulic cylinder that is connected to both the strut assembly at a point distal from the pivot and the chassis of the vehicle. Motion of the strut assembly around the pivot is affected by action of the hydraulic cylinder. In some embodiments, the dual action hydraulic cylinders are in fluid communication with the diagonally opposite hydraulic cylinder such that when one cylinder moves into an extended or retracted position the other diagonally opposite cylinder is urged into the same position. In some embodiments, the wheel suspension assemblies are attached to slidable drawer assemblies on each side of the vehicle.

Abstract: System to control the trim of motorcycles with three or four wheels, the motorcycle having two couples of front and rear wheels, or one front wheel and a couple of rear wheels, or a couple of front wheels and one rear wheel.

Abstract: A damper unit and its employment as part of the suspension system for a vehicle are disclosed. A vehicle of the kind having wheels arranged in left-right pairs has a sprung mass and left and right unsprung masses associated with left and right wheels of a said left-right pair. Respective left and right damper units are mounted between the respective left and right unsprung masses and the sprung mass. Each damper unit has a damper housing defining first and second generally cylindrical chambers therewithin having a common axis. The first and second chambers are separated from each other in the axial direction by an intermediate wall. The first chamber has a first axial end wall at its end remote from the intermediate wall, and the second chamber has a second axial end wall at its end remote from the intermediate wall. A first piston is slidable in sealing engagement with the interior of the first chamber. A second piston is slidable in sealing engagement with the interior of the second chamber.

Abstract: There is provided a hydraulic shock absorber including a spring receiver that is supported so as to be not rotatable with respect to the axle bracket. The spring receiver is divided into a spring receiver base portion that has an outer diameter smaller than an inner periphery of an axle-side tube, and a spring receiver cylindrical portion that is inserted into an inner periphery of the axle-side tube and a suspension spring is seated thereon. A lower end engagement portion provided at a lower end of the spring receiver cylindrical portion is seated on an upper end engagement portion provided at an upper end of the spring receiver base portion, so that the spring receiver cylindrical portion is concentrically set to the axle-side tube.

Abstract: A suspension device has in- and out-configurations for use with a vehicle, including means for damping and/or spring action, the damping and/or spring action being controllable, wherein the controllability of the damping and/or spring action includes a locked or substantially locked state in the out-configuration. A method of using the suspension device with a vehicle is also provided.

Abstract: An air suspension system for a multi-axle vehicle having air bags (4,5; 6,7; 8,9; 10,11; 44 to 49) supporting either side of the axles (2,3; 41 to 43), including separate air lines (18 to 25; 50 to 55) respectively connecting each air bag to a level control valve (16,17; 56,57) via manifolds (26,27; M) and air lines (28,29; 54,55) to independently control air supply to the bags on either side, the separate air lines being of the same size and length to ensure that substantially the same volume of air is supplied to each bag to improve the responsiveness and stability of the system.

Abstract: A security and tracking system to prevent the unauthorized use or access to machinery having hydraulic components whereby the system has a rerouting device housed in a tamperproof casing. The rerouting device might have a selective re-directional valve that can be remotely activated and monitored using wireless signal technology to direct hydraulic fluid to at least two hydraulic circuits, a control center that communicates via wireless signal technology to the rerouting device, a first hydraulic circuit that has a source of fluid, a fluid pumping means, the rerouting device, and a power take off device (PTO) and a second hydraulic circuit that has the source of fluid, the fluid pumping means, and the rerouting device. In operation the rerouting device selectively routs hydraulic fluid about the hydraulic circuit that includes the PTO, thereby rendering the hydraulic equipment functionally operable until the hydraulic fluid is rerouted to the second hydraulic circuit.

Abstract: Altering the damping rate of a vehicle suspension damper. A pressure of a damping fluid is exerted against a second valve mechanism connected to the vehicle suspension damper. The pressure of the damping fluid is increased beyond a threshold of the second valve mechanism that is adjustable by an adjustment member. The adjustment member is exposed through a high pressure side of the vehicle suspension damper. The second valve mechanism is then opened.

Abstract: A controllable suspension system for controlling the relative motion between a first body and a second body includes at least one strut including a magneto-rheological fluid damper. The fluid damper includes a piston rod guide disposed within a damper body. The piston rod guide has a passage therein for receiving a piston rod. A piston rod bearing assembly is disposed in the piston rod guide to engage with and support reciprocal motion of the piston rod. At least a first piston rod seal and at least a second piston rod seal are arranged to seal between the piston rod guide and the piston rod. A fluid chamber is defined between the piston rod guide and the piston rod. A piston rod guide gas charged accumulator is arranged between the piston rod and the damper body.

Abstract: A vehicle roll control system for a vehicle having a pair of front wheels and a pair of rear wheels each rotatable on an axle, comprising a front hydraulic actuator attached to the front torsion bar; a rear hydraulic actuator attached to the rear torsion bar; and control means connected to the front and rear hydraulic actuators and controlling the operation thereof on detection of a predetermined vehicle condition; wherein each front and rear hydraulic actuator comprises a housing, a piston making a sealing sliding fit inside the housing to define a first fluid chamber and a second fluid chamber, and a piston rod connected to the piston and extending through the second fluid chamber and out of the housing; wherein the control means acts on detection of the predetermined vehicle condition to apply a fluid pressure to the first fluid chambers of the front and rear hydraulic actuators and to apply a fluid pressure to the second fluid chambers of the front and rear hydraulic actuators; and wherein the control mea

Abstract: Complementary suspension device applicable between the hydro-pneumatic suspension systems of at least two wheels of a vehicle, which transfer the forces originating in said wheels to the aforementioned complementary device by means of displacement, and/or decanting, of the fluids of said suspension systems through the corresponding conduits, said device comprising two fluid distribution units connected in parallel by means of each joint conduit, between the hydro-pneumatic suspension systems of at least one pair of vehicle wheels, in such a way that for each pair of wheels the first distribution unit is capable of allowing the intake of fluid through the joint conduit with the suspension system of one of the wheels and, at the same time, lets fluid exit through the joint conduit with the suspension system of the other wheel, whereas the second unit only allows the intake of fluid through the joint conduits with the two suspension systems at the same time.

Abstract: A suspension system includes first and second wheel carriers, a stabilizer having a first end and a second end, the stabilizer being coupled to the wheel carriers, a first cylinder/piston unit being arranged between the first end of the stabilizer and the first wheel carrier and a second cylinder/piston unit being arranged between the second end of the stabilizer and the second wheel carrier. Each cylinder/piston unit is a double-acting cylinder/piston unit and the two cylinder/piston units are cross-connected.

Abstract: The present invention relates to a suspension device for the load-bearing and resilient support of a wheel in a motor vehicle. The device comprises at least one spring cylinder with a piston which is guided in a manner moveable relative to it in a pressure cylinder. A driving device converts pivoting movement of a wheel oscillating-crank supporting arm, which movement oscillates about an oscillating-crank axis into the relative movements between the pressure cylinder and the piston. The piston acts counter to an elastically compressible spring medium in order to produce a load-bearing supporting spring force. The driving device is designed as a gearwheel mechanism.

Abstract: A suspension system dampens motion between two components of a vehicle, such as the wheels and the chassis. An assembly of a cylinder and a piston is connected to both components. The piston defines first and second chambers in the cylinder and has a shaft with an end surface exposed to pressure within a third chamber of the cylinder. A first accumulator is connected to the first chamber by a first accumulator valve and a second accumulator valve connects a second accumulator to the second chamber. A damping valve alternately connects the third chamber to either the second chamber or a fluid tank wherein that connection defines the stiffness of the suspension system and is made in response to force acting on the suspension system. A load leveling circuit also is described.

Abstract: A pneumatic suspension system for a vehicle includes pneumatic bellows connectable by means of a valve arrangement to at least one other component of the pneumatic suspension system in order to selectively increase or decrease the amount of compressed air therein. The other component contains at least one volume. Undesirable changes in the amount of compressed air inside the pneumatic bellows arising as a result of pressure compensation are avoided or reduced to a non-disruptive level by a return valve between the valve arrangement and the volume which prevents compressed air from flowing between the pneumatic bellows and the volume in one direction of flow.

Abstract: A roll control system comprising a front torsion bar; a front first hydraulic actuator attached to the front torsion bar; a rear torsion bar; a rear first hydraulic actuator attached to the rear torsion bar; and control means connected to the hydraulic actuators and controlling the operation thereof on detection of a predetermined vehicle condition; wherein each hydraulic actuator comprises a first fluid chamber and a second fluid chamber; wherein the control means comprises a source of fluid pressure, a fluid reservoir, a pressure control valve fluidly connected between the pressure source and the reservoir, two pressure relief valves each having two positions to selectively fluidly connect the fluid chambers of the hydraulic actuators either to the pressure source or to the fluid reservoir, and a directional valve fluidly connected between the pressure relief valves and the fluid chambers of the hydraulic actuators; wherein the pressure relief valves and the directional valve are positioned on detection of

Abstract: A suspension system for a vehicle, including: (a) four displacement force generators each having an electromagnetic motor and configured to generate, based on a motor force generated by the motor, a displacement force forcing sprung and unsprung portions of the vehicle toward or away from each other; and (b) a controller configured to control the displacement force generated by controlling operation of the motor. The controller includes (b-1) a target-value determining portion configured to determine a target value of a displacement-force-relating amount of each of the four displacement force generators, and (b-2) a target-value reducing portion configured to reduce the target value of the displacement-force-relating amount of a subjected device as one of the four displacement force generators, in accordance with a certain rule.

Abstract: A ride control system for a motorcycle having an oil-containing fork having an air space. The control system includes a control unit having a reservoir and a valve in flow communication with the air space of the fork and the reservoir. The valve is configured to enable air to substantially freely pass from the air space of the fork to the reservoir during a relatively low speed impact experienced by the fork, and to inhibit air from passing from the fork to the reservoir during a relatively high speed impact.

Abstract: A front fork, which is interposed between a vehicle body and an axle to restrain a change in vehicle attitude, comprises a fork body (101) including a reservoir chamber (106) partially filled with gas and performing an expansion and contraction operation, a reservoir tank (102) partially filled with gas and communicating with the reservoir chamber (106) through a flow path (103) in which hydraulic oil flows, an on-off valve (35) switching between opening and closing of the flow path (103), and a relief valve (40) accepting flow of hydraulic oil from the reservoir chamber (106) toward the reservoir tank (102) when a pressure of the reservoir chamber (106) reaches a predetermined pressure.

Abstract: The present invention relates to a suspension device for the load-bearing and resilient support of a wheel in a motor vehicle, comprising at least one spring cylinder with a piston, which is guided in a manner moveable relative to it in a pressure cylinder, and comprising a driving device for converting pivoting movements of a wheel oscillating-crank supporting arm, which movements oscillate about an oscillating-crank axis, into the relative movements between the pressure cylinder and piston, the piston acting counter to an elastically compressible spring medium (FM) in order to produce a load-bearing supporting spring force (F), the driving device being designed as a gearwheel mechanism.

Abstract: Four shock absorbers are connected to a control cylinder. The control cylinder includes a housing body portion having two cylinder chambers which are divided by a partition wall portion; and a piston assembly which is formed by coupling two pistons with each other using a coupling rod. Two outer side control chambers and two inner side control chambers are connected to respective absorber chambers. Pressure receiving areas of outer side pressure-receiving surfaces and inner side pressure-receiving surfaces of the pistons and damping characteristics of the shock absorbers are set such that a direction in which the piston assembly moves in a region where an operation speed is low is opposite to a direction in which the piston assembly moves in a region where the operation speed is high.

Abstract: A trailer for transporting a pontoon boat behind a tow vehicle. The trailer is provided with wheel assemblies that can be moved longitudinally on the trailer's frame to adjust the load on the tongue of the trailer and is provided with rails that can be adjusted in width for receiving the pontoons of boats with different pontoon spacing. The trailer frame can be pneumatically raised and lowered on pivoting wheel brackets and each set of pontoon rails is provided with several pneumatically retractable rollers that can be raised and retracted relative to their associated rails to assist in loading and unloading a pontoon boat from the trailer. When the boat is not being transported, the rails and associated rollers can be removed from the trailer so that the trailer can function as a flatbed trailer.

Abstract: A wheel suspension for vehicles. The invention relates to both double axle vehicles and single axle vehicles. Feasible areas of use are: prams, carts (pulled manually or by a vehicle), walkers, wheel chairs, skateboards, luggage carts and motor vehicles. It is significant for the wheel suspension that the centre axles (15a, 15b) of wheels (11a, 11b) of a set of wheels are connected to elements (14a, 14b) that extend in the travelling direction of the vehicle, that these elements (14a, 14b) are hingedly/pivotally connected to a frame (1?) of the vehicle, that the centre axles (15a, 15b) for adjacent wheels (11a, 11b) are located at a certain distance from each other in the longitudinal direction/travelling direction (2) of the vehicle.

Abstract: Complementary suspension device applicable between the hydro-pneumatic suspension systems of at least two wheels of a vehicle, which transfer the forces originating in said wheels to the aforementioned complementary device by means of displacement, and/or decanting, of the fluids of said suspension systems through the corresponding conduits, said device comprising two fluid distribution units connected in parallel by means of each joint conduit, between the hydro-pneumatic suspension systems of at least one pair of vehicle wheels, in such a way that for each pair of wheels the first distribution unit is capable of allowing the intake of fluid through the joint conduit with the suspension system of one of the wheels and, at the same time, lets fluid exit through the joint conduit with the suspension system of the other wheel, whereas the second unit only allows the intake of fluid through the joint conduits with the two suspension systems at the same time.

Abstract: The present invention provides a method and system for electronic shock absorbing by adjusting the retractile status of a retractable absorber, wherein an acceleration sensor is fixed on a vehicle body at a predetermined direction and angle to detect the signal of acceleration vectors both along the vertical direction and along the longitudinal and transverse direction of the vehicle, and then transmit the signal to an information processing and controlling device to set the retractile status of the retractable absorber to realize shock absorbing.

Abstract: A vehicle suspension system for use with a vehicle includes a first hydraulic cylinder, a second hydraulic cylinder, and a fluid circuit. The first hydraulic cylinder and the second hydraulic cylinder each include an upper chamber and a lower chamber. The fluid circuit is hydraulically coupled to the first hydraulic cylinder and the second hydraulic cylinder and includes a valve that is movable between a first position and a second position. When the valve is in the first position, the upper and lower chambers of each hydraulic cylinder are hydraulically coupled to the opposite chamber of the other cylinder. When the valve is in the second position, the upper chamber of each hydraulic cylinder is coupled to the lower chamber of the same cylinder. The valve is configured to move between the first position and the second position in response to manual input.