Abstract: A vehicle platform includes a first wheel, a second wheel, and a first orientation keeper to move the first wheel in a vehicle width direction and keep an orientation of the first wheel with respect to a front-rear direction of a vehicle during movement of the first wheel. The first orientation keeper includes a first center body, a first wheel arm, and a first rotation actuator. The first center body is between the first wheel and the second wheel. The first wheel arm is rotatably connected to the first center body, extends between the first center body and the first wheel, and supports the first wheel. The first rotation actuator is operable to rotate the first wheel arm relative to the first center body such that the first wheel moves toward or away from the first center body.

Abstract: A support system includes a primary actuator that transfers force between a sprung mass and an unsprung mass. A control system operates the primary actuator to provide additional control when a damper exceeds a capacity threshold. The control system changes the capacity threshold according to the environmental condition.

Abstract: A boom lift includes a base having a first end and an opposing second end, a turntable coupled to the base, a boom coupled to the turntable, an assembly pivotably coupled to the first end of the base, and a first actuator coupled to the first end of the base and the assembly. The assembly includes a tractive element. The assembly extends from the base such that the tractive element is longitudinally offset from and spaced forward of the first end and the opposing second end of the base.

Abstract: A system and method for leveling a selected surface of a structure. The system includes a handheld mobile device and a platform leveling assembly (PLA) supportable on a structure to be leveled. The PLA includes a PLA controller and a PLA receiver communicatively coupled with the PLA controller. The handheld mobile device includes a tilt sensor configured to sense an attitude of a selected surface on which the handheld mobile device is placed; and a mobile device controller communicatively coupled to the tilt sensor and the transmitter and configured to receive signals from the tilt sensor indicating the attitude of the selected surface on which the handheld mobile device is placed.

Abstract: Tipping over of a work machine is prevented. The work machine includes: a vehicular body; a rear axle attached to the vehicular body to be capable of undergoing a roll motion with respect to an axis extending in a front-rear direction of the vehicular body; and a controller. The controller acquires stability of the center of gravity of the vehicular body, and controls the roll motion of the rear axle with respect to the vehicular body based on the stability.

Abstract: A suspension element includes a housing, a first joint, and a second joint. The housing is configured to couple a tractive element assembly to a vehicle. The housing has a first end configured to engage a portion of the vehicle and a second end configured to interface with the tractive element assembly. The first joint includes a first actuator and a first resilient member. The first actuator is configured to facilitate linear extension and retraction of the suspension element. The second joint includes a second actuator and a second resilient member. The second actuator is configured to facilitate rotational movement of the suspension element. The first resilient member and the second resilient member are configured to support a static load of the vehicle.

Abstract: Disclosed herein are hydraulic actuators and methods for the operation of actuators having variable relative pressure ratios. Further disclosed are methods for designing and/or operating a hydraulic actuator such that the actuator exhibits a variable relative pressure ratio. In certain embodiments, the relative pressure ratio of the hydraulic actuator may be dependent on one or more characteristics (such as, for example, frequency or rate of change) of an oscillating input to the hydraulic actuator.

Abstract: A suspension system for a vehicle and method for operating the same includes a shock absorber housing having a longitudinal axis, a spring disposed around the shock absorber housing, a retainer collar disposed around the shock absorber housing and an actuator engaged to the retainer collar. The actuator moves at least a portion of the retainer collar to move the spring in a direction corresponding the longitudinal axis. A switch generates a ride height position signal. A controller is coupled to the actuator and the switch. The controller controls a position of the actuator in response to the ride height position signal.

Abstract: A machine operating on a work surface includes a boom member, a feed assembly, a work device, a movable carrier including a lower structure and an upper structure movably coupled with the lower structure, and an actuator assembly adapted to move the upper structure relative to the lower structure. The machine also includes a sensor module configured to generate a first signal indicative of a first pitch angle. The machine further includes a control module configured to receive the first signal indicative of the first pitch angle. The control module is also configured to generate a second signal for controlling a movement of the actuator assembly based on the first signal. The control module is further configured to transmit the second signal to the actuator assembly in order to move the upper structure by a second pitch angle.

Abstract: An assembly for correcting an attitude of at least a selected portion of a structure, where the assembly includes a controller affixed to a structure operatively coupled with one or more jacks operable to change the attitude of the structure; and a remote device configured to communicate wirelessly with the controller to change the attitude of a selected portion of the structure. Also disclosed is a method for adjusting an attitude of a movable structure.

Abstract: An apparatus for adjusting a vehicle height, the apparatus including a cylinder coupled to a suspension arm and having a pressure chamber therein, a hollow cylinder cap coupled to the cylinder, a first piston disposed to be movable upward or downward in the pressure chamber and having a lifting hole portion penetratively formed, a second piston disposed to be movable upward or downward in the lifting hole portion and having an upper portion to which a leaf spring seating part on which a leaf spring is seated is coupled, and a height adjustment unit connected to the cylinder and configured to selectively adjust a height of at least any one of the first piston and the second piston by changing a pressure of a working fluid in the pressure chamber.

Abstract: A lawn mower front wheel positioning system that provides adjustment of lateral positioning of a front wheel of the mower. The front wheel positioning system includes a wheel support arm, a wheel support member, and a wheel positioning arm having an adjustable length. The wheel positioning arm having a proximal end that couples to the wheel support member and a distal end that couples to the wheel support arm. A first end of the wheel support arm couples to the front wheel. A second end of the support arm couples to the support member by way of a support arm wheel pivot that defines a wheel pivot axis. The wheel support arm and the front wheel rotate about the wheel pivot axis responsive to adjustment of the length of the wheel positioning arm.

Abstract: This disclosure details cargo management systems for monitoring the regulatory compliance of cargo positioned on a vehicle. Exemplary cargo management systems may be configured to estimate a distance an item of cargo extends beyond a perimeter of the vehicle and then compare the estimated distance with a cargo-related regulation to confirm compliance of the item of cargo with the cargo-related regulation. The cargo management system may further be configured to detect positional changes of the item of cargo to ensure continued compliance of the item of cargo with the cargo-related regulation during vehicle operation. The cargo management system may issue an alert when the item of cargo is determined to be non-compliant with the cargo-related regulation or when the item of cargo shifts during vehicle operation.

Abstract: A track driven work machine including a body, a first track laying assembly pivotally connected to the body, and a second track laying assembly pivotally connected to the body. The second track laying assembly is spaced apart from the first track laying assembly in a direction transverse to a running direction of the track laying assemblies. In order to navigate uneven grounds, the track driven work machine includes a hydraulic system for synchronizing pivotal movement of the first and second track laying assembly and which is configured to pivot the second track laying assembly in an opposite direction to the first track laying assembly when the first track laying assembly is pivoted in a first direction, and vice versa.

Abstract: The invention resides in a system and method for determining the manner in which a vehicle is driven. The system comprises a processor comprising an input configured to receive dynamic ride data from at least one on-board vehicle dynamic ride sensor, wherein the processor is configured (i) to calculate an output signal which is indicative of whether the dynamic ride data exceeds at least one dynamic ride data threshold value for a predetermined period of time; and (ii) to compare the output signal with at least one output threshold to determine the manner in which the vehicle is driven. The processor comprises an output configured to send a control signal to one or more vehicle components, wherein the control signal is indicative of the manner in which the vehicle is driven.

Abstract: A suspension device includes: a suspension including a damping device which damps a force generated between a vehicle body and a wheel; and a damping force control unit that increases a damping force of the damping device so as to be greater than the damping force generated when an acceleration of change in a stroke amount is less than a predetermined value determined in advance, when the acceleration of the change in the stroke amount is equal to or greater than the predetermined value, in which the stroke amount is an amount of displacement from a reference position of the wheel with respect to the vehicle body in an extension direction of the suspension.

Abstract: A steerable vehicle suspension can include an axle, at least one retractor having a length that decreases in response to a pressure increase applied to the retractor, and at least one wheel spindle. Resistance to rotation of the wheel spindle relative to the axle increases in response to the pressure increase applied to the retractor. A method of operating a steerable vehicle suspension of a vehicle can include allowing steering knuckles rotatably mounted at opposite ends of an axle to rotate relative to the axle while the vehicle moves forward, and applying an inwardly directed force simultaneously to each of the steering knuckles. Another steerable vehicle suspension can include two rotatably mounted steering knuckles, and two retractors connected to the steering knuckles. An inwardly directed force is applied by each retractor to a respective one of the steering knuckles in response to pressure applied to the retractors.

Abstract: An electric suspension apparatus includes electric actuators provided for a plurality of wheels, respectively, an acceleration sensor disposed in each of the electric actuators, the acceleration sensor detecting a first acceleration, and an electric suspension control ECU controlling each of the electric actuators based on the first acceleration, and the electric suspension control ECU decreases a control amount to the electric actuator, in a case where a first speed based on the first acceleration in an up-down direction is equal to or less than a predetermined speed.

Abstract: A support system for a vehicle includes a base and at least a first and a second support arm. Each of the first and the second support arms include a base end pivotally coupled to the base through a respective hinge assembly. Each of the first and the second support arms further include a distal end opposite the base end. The support system also includes a respective wheel assembly coupled to each distal end. Each wheel assembly includes an independently powered and steerable wheel configured to engage a travel surface, a propelling motor configured to drive a respective first support arm between a stowed condition and a deployed condition unaided while the vehicle remains stationary, and a steer actuator configured to change an angle of the wheel with respect to a respective support arm.

Abstract: A levelling assembly is provided, for levelling an upper carriage assembly of a machine with respect to an undercarriage assembly having a first track roller frame and the second track roller frame. A levelling body is rotatably coupled to the first track roller frame and the second track roller frame and defines a first side and a second side laterally opposite to the first side. The levelling assembly includes a first pair of fluid actuators for movably coupling first side of the levelling body with the first track roller frame and a second pair of fluid actuators for movably coupling second side of the levelling body with the second track roller frame. The first and the second pair of fluid actuators move the levelling body between a fore tilted position and an aft tilted position relative to the first and the second track roller frames.

Abstract: A working machine includes an undercarriage, a main frame, a swing bearing supporting the undercarriage from the main frame, a swing motor configured to pivot the main frame on the swing bearing about a pivot axis, a boom extending from the main frame along a working direction, and a pivot angle sensor configured to provide a pivot angle signal corresponding to a pivot position of the main frame relative to the undercarriage about the pivot axis. A controller is configured to receive the pivot angle signal and to drive the swing motor automatically.

Abstract: A lawn maintenance vehicle includes an adjustable seat assembly, wherein the seat assembly is rotatable relative to a frame of the vehicle when the vehicle is operated on a sloped surface. The seat assembly is rotatable in order to maintain the operator in a substantially vertical seated alignment while operating the vehicle on a sloped surface. The seat assembly is also rotatable when the vehicle is in a zero-turn or tight-turn maneuver, wherein the seat is rotated toward the center of turning radius to offset the centrifugal forces experienced by the operator during such a maneuver.

Abstract: An electric vehicle includes a lateral self-stabilization system and may further include a fore-aft self-stabilization system. The lateral self-stabilization system may include a controller configured to cause an actuator to laterally tilt a frame of the vehicle based on sensed information relating to an orientation of the vehicle, or portion thereof, about a roll axis. The frame of the vehicle may include any suitable structure configured to be laterally tilted by the actuator relative to an axle of the vehicle. The fore-aft stabilization system may include a motor controller configured to drive a motor of the vehicle based on sensed information relating to a pitch angle of the vehicle. In some examples, the vehicle is a robotic vehicle.

Abstract: An agricultural vehicle having a chassis, wheels, a power unit, and a header. The header has a center section, at least one wing section extending laterally from the center section, and a wing section support. The center section is movable relative to the chassis, the wing section is movable relative to the center section, and the wing support is movable relative to the wing section. The combine has a control system that is configured to determine that the combine is configured to drive at a road-driving speed, and in response to such determination: operate a center section actuator to move the center section to a raised center section position, operate a wing section actuator to move the wing section to a raised wing section position, and operate a wing support actuator to move the wing support to a raised wing support position.

Abstract: A combine harvester with a variable length wheelbase. For example, a combine harvester may have a chassis defining a forward end and a rear end, a feeder house at the forward end of the chassis, a first set of ground-engaging elements supporting the forward end of the chassis, and a second set of ground-engaging elements supporting the rear end of the chassis. The second set of ground-engaging elements are configured to move forward and rearward relative to the chassis.

Abstract: A vehicle jacking assembly for raising a vehicle includes a plurality of cylinders, each of which is configured to couple to a frame of a vehicle proximate to a respective wheel of the vehicle. The cylinder comprises a plurality of nested sections so that the cylinder is selectively extensible. An actuator that is coupled to the vehicle is operationally coupled to the plurality of cylinders and an electrical circuit of the vehicle. The actuator is positioned to selectively actuate the plurality of cylinders to extend the cylinders from the frame of the vehicle so that the cylinders contact a surface. The plurality of cylinders thus is configured to raise the vehicle.

Abstract: An unmanned vehicle chassis includes: a chassis bracket, a front wheel assembly, a middle wheel assembly, and a rear wheel assembly that engage the chassis bracket, a driving unit disposed on the chassis bracket and configured to drive the unmanned vehicle chassis to move, a rocker arm connected to the chassis bracket, where the rocker arm rotates around an axis of the middle wheel assembly, and the middle wheel assembly and the rear wheel assembly are mounted at both ends of the rocker arm, respectively, and connected to the chassis bracket through the rocker arm, and a driving mechanism disposed on the chassis bracket and configured to control the rocker arm to move.

Abstract: The ECU of the stabilizer control apparatus determines, based on a high frequency component of a wheel acceleration and a low frequency component of a wheel speed difference, whether a road surface state is a rough road state or a smooth road state. When the road surface state is determined to be the rough road state, the ECU sets a turning determination threshold to a rough road threshold. When the road surface state is determined to be the smooth road state, the ECU sets the threshold to a smooth road threshold. When a turning determination parameter is greater than the threshold, the ECU sets each of first, second, and third cylinders to a lock state to increase rigidity of stabilizers. When the turning determination parameter is smaller than the turning determination threshold, the ECU sets each of the cylinders to a free state to decrease the rigidity of the stabilizers.

Abstract: A system and method are provided for spacing railcars of a train apart from each other with a predetermined gap in between. Embodiments include a railcar spacing tool having a hydraulic cylinder with brackets at opposing ends for contacting the frame of each of a pair of adjoined adjacent railcars to be spaced from each other, and a cylinder support frame attached to the cylinder and movably attached to a support vehicle such that the support frame is movable from a retracted position to an extended position where the brackets are between the frames of the pair of railcars. After moving the cylinder support frame to the extended position, the brackets are positioned in contact with the railcar frames, and the cylinder is engaged to create the predetermined gap between the railcars. The railcars' brakes are applied to preserve the gap, and the spacing tool is then removed.

Abstract: An electro-mechanical automatic self-leveling device is provided for use on motorized chair seats. The device may include a pendulum assembly consisting of neodymium magnets attached to an inertia-dampened pendulum and a printed circuit board (PCB) with a hall effect sensor and processing circuitry that will develop proportional correction signals to be amplified by a high-current bi-directional motor driver. This configuration is assembled in a case attached to the motorized chair seat via a mounting bracket and clamping knob, and a cable from the device connects to the chair's seat tilt motor and power supply. Various switches may be included to reset the device in case of overheating and to switch between automatic and manual leveling. In alternative embodiments, the auto-leveling mechanism may be integrated into the motorized chair seat design rather than a separate device that can be attached to the chair seat after-market and independent of the chair's controller.

Abstract: A processing system for a motorized mobile system includes at least one sensor to measure one or more kinematic states of an object and at least one processor to use at least one state estimation filter and at least one object kinematic model to predict a first kinematic state estimate of the object and output the first predicted kinematic state estimate for use by at least one other process of the motorized mobile system. The processor uses the first predicted kinematic state estimate and the one or more measured kinematic states to determine a second kinematic state estimate of the object and uses the second kinematic state estimate as an input to the state estimation filter to predict another kinematic state estimate of the object.

Abstract: In vehicle platooning, when road surface information is received from a preceding vehicle, an ECU determines whether a specific spot on a road included in the road surface information can be avoided. That is, the ECU determines whether avoidance control can be performed. When it is determined that the avoidance control can be performed, the ECU transmits the road surface information received from the preceding vehicle to a following vehicle, and performs the avoidance control to avoid the specific spot on the road. In contrast, when it is determined that the avoidance control cannot be performed, the ECU ends a process without performing the avoidance control.

Abstract: A harvesting machine includes a chassis, a ground-engaging mechanism for supporting the chassis, and a tank assembly mounted to the chassis for storing a crop material. The tank assembly includes a retractable door for at least partially covering an opening formed in a top of the tank assembly. A mobile sensor assembly includes a rod and a sensor for detecting a weather condition, such that the rod includes a first end coupled to the retractable door and a second end to which the sensor is coupled. The retractable door is operably moved between an open position and a closed position, and the mobile sensor assembly is rotatably moved between a deployed position and a stowed position as the door is moved between the open and closed positions, respectively.

Abstract: An assembly for correcting an attitude of at least a selected portion of a structure, where the assembly includes a controller affixed to a structure operatively coupled with one or more jacks operable to change the attitude of the structure; and a remote device configured to communicate wirelessly with the controller to change the attitude of a selected portion of the structure. Also disclosed is a method for adjusting an attitude of a movable structure.

Abstract: The present invention relates to a system for delivering medical services in a mobile setting that includes a frame assembly, where said frame assembly is mounted to an enclosed portable compartment. The frame assembly forms an examination and therapy area for administering a multitude therapy modalities. The therapy area includes a plurality of tables convertibly and plurality of cabinets integrated into the frame assembly. A grouping of training equipment removably engages with the frame assembly related to various therapy techniques. The enclosed portable compartment may be an interior of a van or an interior of a portable pod.

Abstract: Systems and methods are disclosed herein for secure communication of data between motorized mobile systems (MMS) and external devices, systems, networks, and servers. The data may include one or more of user, health, environment, and system data retrieved from one or more sensors located in, on, and around an MMS. The MMS stores and/or transmits the sensor data using secure protocols when the sensor data relates to personal information, such as personal health data, to protect the privacy of the user.

Abstract: An all-terrain vehicle for civil protection activities includes a vehicle structure with at least one module for transporting persons and/or material, and a plurality of legs bearing respective wheel assemblies or track assemblies. Each leg is pivotably mounted about a first transverse axis. One first end of the leg carries a wheel assembly or a track assembly and a second end is freely mounted pivoting about the first transverse axis on a first support which is carried by the vehicle structure. An electronically-controlled actuator adjusts an angular position of the first support about a first transverse axis. Between the first support and the leg structure two spring-shock absorber assemblies are interposed, which extend along the leg.

Abstract: A suspension system includes a vehicle frame component, a suspension component coupled to and movable relative to the vehicle frame component, a flexible sensor, and a rotatable joint. The flexible sensor is elongated between a first end and a second end, and the first end of the flexible sensor is fixed relative to one of the vehicle frame component or the suspension component. The rotatable joint couples the second end of the flexible sensor to the other of the vehicle frame component or the suspension component.

Abstract: System and method for nullifying one or more of lateral and longitudinal acceleration forces experienced by an occupant of a vehicle in a seated or standing position while the vehicle is traveling along a travel plane, including: a chassis structure; and an occupant cell one of coupled to and defined by the chassis structure; wherein one or more of the chassis and the occupant cell are configured to pivot one or more of: laterally at a longitudinal pivot point with respect to the travel plane; and longitudinally at a transverse pivot point with respect to the travel plane. Optionally, the chassis structure is configured to pivot one or more of laterally and longitudinally with respect to one or more wheel mechanisms operable for traveling over the travel plane. Optionally, the occupant cell is configured to pivot one or more of laterally and longitudinally with respect to the chassis structure.

Abstract: At least one controller configured to control an actuator of an active suspension system. The at least one controller includes circuitry configured to determine an actuator state, and apply the actuator state and a commanded state to an inverse model of the actuator to produce an actuator command. The circuitry is configured to produce the actuator command by a process that includes performing low pass filtering and phase compensation to correct a phase introduced by the low pass filtering.

Abstract: A suspension system for a work vehicle includes an axle bar, an inner control member, an outer control member, and a slide housing. The axle bar extends through the inner control member, the outer control member, and the slide housing. The axle bar is non-rotatably coupled to the slide housing and is configured to pivot with the slide housing and relative to the inner control member and the outer control member.

Abstract: A rephasing system may include a first hydraulic cylinder, a second hydraulic cylinder, a first rephasing valve, a second rephasing valve and a controller. The first hydraulic cylinder and the second hydraulic cylinder include first and second pistons, respectively. A first hydraulic fluid line connects a hydraulic supply to a first side of the first piston while a second hydraulic fluid line connects a second side of the first piston to a first side of the second piston. The first rephasing valve fluidly couples the first side of the first piston to the first side of the second piston while the second hydraulic fluid line fluidly couples the second side of the second piston to the hydraulic supply. The controller selectively opens and closes the first and second rephasing valves to re-phase the first and second pistons.

Abstract: A tagged excavation element, including an excavation element body and a tagging device securable to the excavation element body. The tagged excavation element is characterized in that the tagging device includes a man-made radioactive source. Typically, but not exclusively, the excavation element body comprises a shroud or tooth of an excavation bucket of a ground excavation tool (GET). A method is provided for manufacturing the tagged excavation element, and for detecting the tagged excavation element.

Abstract: A drive device for a vehicle, which has an electric motor, a power electronics unit and a transmission. The power electronics unit is arranged between a shaft of the electric motor and a shaft of the transmission.

Abstract: A method for leveling a jacked vehicle may involve: (a) sensing a pitch angle of the vehicle; (b) sensing a roll angle of the vehicle; (c) producing a pitch reference value that is related to the sensed pitch angle of the vehicle; (d) producing a roll reference value that is related to the sensed roll angle of the vehicle; (e) extending a vehicle jack that affects at least the pitch angle of the vehicle at a speed that is related to the pitch reference value; (f) extending a vehicle jack that affects at least the roll angle of the vehicle at a speed that is related to the roll reference value; and (g) repeating (a)-(f) until the sum of the pitch and roll angles falls below a predetermined angle.

Abstract: An aerocar with a dual mode suspension system configured to operate in a roadable mode and a flight mode. The aerocar may include a front suspension assembly having a front axle, and a rear suspension assembly having a rear axle. A conduit system provides a hydraulic fluid in fluid communication between the front suspension assembly and the rear suspension assembly. An auxiliary hydraulic fluid reservoir is provided in fluid communication with the conduit system, and configured to selectively maintain or interrupt fluid communication between the front suspension assembly and the rear suspension assembly to adjust damping of the front suspension assembly. A controller may be provided, configured to direct the flow of hydraulic fluid from the rear suspension assembly to the front suspension assembly, for example, when a stroke of the rear suspension exceeds a predetermined value during landing.

Abstract: In a riding mower having a frame, a mower deck supported beneath the frame, a chair on said frame and a source of motive power also supported on said frame and including two hydraulic transaxles depending beneath the frame to each selectively rotate a drive wheel. The frame is supported on forward and rear wheel assemblies with a supporting wheel. The transaxles are supported beneath the frame and pivotally secured thereto by a flange captivating vibration pillows and proximate the driven wheel and an inner pivot rod secured to the frame by apertures in downwardly depending tabs.

Abstract: In a riding mower having a frame, a mower deck supported beneath the frame, a chair on said frame and a source of motive power also supported on said frame and including two hydraulic transaxles depending beneath the frame to each selectively rotate a drive wheel. The frame is supported on forward and rear wheel assemblies with a supporting wheel. The transaxles are supported beneath the frame and pivotally secured thereto by a flange captivating vibration pillows and proximate the driven wheel and an inner pivot rod secured to the frame by apertures in downwardly depending tabs.

Abstract: A replenishment passage connects a compressor to a tank, and a first check valve is provided in the middle of the replenishment passage. A supply/discharge passage connects the tank to air suspensions. A supply/discharge switching valve is provided in the middle of the supply/discharge passage, and suspension control valves are provided at a location between the supply/discharge switching valve and the air suspensions. A discharge passage connects the supply/discharge switching valve to a suction port of the compressor, and a discharge passage open/close valve is provided in the middle of the discharge passage. When a vehicle height is lowered, air within the air suspensions is guided to the suction port of the compressor through the discharge passage, compressed by the compressor, and supplied into the tank.

Abstract: A vehicle stabilization system including a frame; a wheel; a control arm connected to the frame and the wheel; a fluid spring connected to the frame and the control arm; a stabilizer connected to the frame and operable between a retracted and extended position; a reservoir; and a fluid manifold connected to the fluid spring and the chamber, fluidly coupling the spring interior and stabilizer chamber to the reservoir interior. A vehicle stabilization method including maintaining an orientation of the vehicle frame, coupling the frame to a support surface using a stabilizer by introducing a fluid to a chamber of the stabilizer, and retracting a wheel by reducing a quantity of fluid within a fluid spring coupling the wheel to the frame.