Abstract: A bicycle includes a front wheel and a rear wheel and a frameset supported on the front wheel and the rear wheel. The frameset includes a main frame and a front fork rotationally coupled to the main frame. The main frame includes a top tube, a head tube rotationally supporting the front fork, a down tube coupling the head tube to a bottom bracket, a seat tube extending downward from the top tube and including a lower end spaced from the bottom bracket, a seatstay extending rearward from the lower end of the seat tube, and a strut member extending forward from the lower end of the seat tube and connecting the seat tube to the down tube.

Abstract: The saddle-ride vehicle includes: a vehicle body frame; a hydraulic braking device that brakes a rear wheel; and a reservoir tank that stores a brake fluid of the braking device, the reservoir tank being supported on the vehicle body frame via a bracket, the reservoir tank being covered from an outside in a vehicle width direction by the vehicle body frame.

Abstract: A two-wheeled vehicle includes a frame assembly having a front end and a rear end extending along a longitudinally-extending centerline, a front ground-engaging member operably coupled to the front end of the frame assembly at a front rotational axis, and a rear ground-engaging member operably coupled to the rear end of the frame assembly at a rear rotational axis. A wheel base is defined between the front and rear rotational axes and a vertically-extending centerline of the vehicle extends vertically at the midpoint of the wheel base and is perpendicular to the longitudinally-extending centerline. The vehicle also includes a fuel tank, an airbox assembly, and a battery all positioned relative to the vertically-extending centerline of the vehicle.

Abstract: In a suspension for a vehicle including a pre-load adjustment mechanism, the pre-load adjustment mechanism includes a pre-load controller and an intermediate member, the pre-load controller being arranged at one end portion and receiving a spring, the intermediate member being sandwiched between the pre-load controller and the spring, the pre-load controller fits in an outer circumferential portion of the one end portion and is movable in the stroke direction by turning on a thread portion of the outer circumferential portion, the one end portion includes a long groove portion in the outer circumferential portion, the long groove portion extending in the stroke direction, the intermediate member has a ring-shape and is movable in the stroke direction, the outer circumferential portion being inserted to the ring-shape, and the intermediate member includes an engagement portion that engages with the long groove portion.

Abstract: A bicycle frame with an improved suspension system. The bicycle frame includes an adjustable dropout assembly that provides adequate shock absorption without affecting or being affected by the chain length or the pedaling action of the bicycle. The bicycle frame includes a uni-axis system that increases the efficiency and performance of the bicycle while eliminating latter movement found in traditional frames. The bicycle frame includes a micro-adjustable suspension system that allows the rider to easily adjust the suspension of the frame to precise measurements quickly and without additional tools.

Abstract: A suspension structure utilized in a driving assembly of a vehicle with a first suspension arm, a second suspension arm, a third suspension arm and a shock absorber component is provided. The first suspension arm has a first fixed end and a first swing end opposite to the first fixed end. The second suspension arm has a second fixed end and a second swing end opposite to the second fixed end. The third suspension arm has a front swing end and a rear swing end opposite to the front swing end. The shock absorber component is disposed between the first suspension arm and the second suspension arm, and has two ends pivotally connected to the first suspension arm and the second suspension arm respectively. The shock absorber component is adapted to absorb an impact force by deforming while the impact force generated.

Abstract: A bicycle sliding dropout comprising a splitting body and a slider slidably engaging the splitting body. The splitting body comprises an inner body and an outer body, the inner and outer bodies being configured to abut each other vertically and matingly engage via a mechanical interface.

Abstract: A rear suspension system for bicycles, such as freeride, downhill and trail-style mountain bikes. The suspension system includes a rear suspension for coupling the rear wheel of the bicycle to the bicycle frame, a rear shock absorber disposed entirely in front of the seat tube of the frame and a linkage for operatively coupling the rear suspension to the rear shock absorber. The linkage intersects the longitudinal axis of the seat tube for transmitting rear suspension forces around the seat tube to the rear shock absorber. The seat tube is preferably continuous and is disposed so that the bicycle seat is adjustable over a full range of seat positions. Additionally, the seat tube and rear suspension system are configured so that the rear wheel and rear suspension will not contact the seat tube, seat, or bicycle rider even when the rear suspension system is in a fully compressed, forward position.

Abstract: A shock-absorbing bicycle frame includes a front frame, a rear frame, and a shock-absorbing unit. The rear frame includes a seat stay and a chain stay interconnected to form an angle therebetween. The shock-absorbing unit includes a first flexible member connected removably to the chain stay and the front frame, and a second flexible member connected between the chain stay and the front frame and disposed directly above the first flexible member. The first and second flexible members are deformable in first and second directions, respectively. The first direction intersects the second direction. As such, when subjected to an external force, the first and second flexible members are deformed to absorb shock.

Abstract: A bicycle frame can have a main frame, a sub-frame and a shock. The sub-frame can move in relation to the main frame and the shock can be used to regulate that relationship. A linkage can also be used to regulate the relationships and control the rotation. The shock can further have a pair of extension arms to span a seat tube which is part of the main frame.

Abstract: Described are dropout assemblies for bicycles, which include a receiver and a dropout. The dropout assemblies can allow a single bicycle frame to be compatible with various drivetrains, wheels and other components and accessories. The receiver may include inner and outer mounting surfaces on which a dropout may be mounted. The dropout may include first and second mounting surfaces formed to be mounted on the inner or outer mounting surfaces of the receiver. The axle spacing may be adjusted by mounting of either the first or second surface of the dropout on the inner or outer surface of the receiver.

Abstract: A trailer having a forward frame section, a rearward frame section, and two trailing arm suspension links forming an independent suspension system without a unitary cross axle. The trailing arm suspension links further include (i) a pivot joint connected to the forward frame section, (ii) a wheel hub assembly including a spindle; and (iii) a shock mount including a bracket position rearward of the spindle. The shock absorbing mechanism has a first end pivotally connected to the shock mount and a second end pivotally connected to the rear frame section rearward of the shock mount.

Abstract: A bicycle frame with an improved suspension system. The bicycle frame includes an adjustable dropout assembly that provides adequate shock absorption without affecting or being affected by the chain length or the pedaling action of the bicycle. The bicycle frame includes a uni-axis system that increases the efficiency and performance of the bicycle while eliminating latter movement found in traditional frames. The bicycle frame includes a micro-adjustable suspension system that allows the rider to easily adjust the suspension of the frame to precise measurements quickly and without additional tools.

Abstract: A bicycle comprising a front triangle and a rear wheel having a rear wheel axis, a rear wheel suspension system further comprising a link further comprising a first pivotal axis for connection to said front triangle and a second pivotal axis for connection to a rear wheel swingarm, wherein the distance from said second pivotal axis to a first vertical plane decreases during a first portion of suspension compression and increases during a second portion of suspension compression; and wherein said first vertical plane is defined as a plane which is perpendicular to the ground and offset in the direction of the rear wheel with respect to the first and second pivotal axis. During the first portion of suspension compression and during the second portion of suspension compression the front triangle remains stationary with respect to the first vertical plane.

Abstract: A braking device removably attachable to a skateboard having a plurality of wheels, the device comprising a plurality of wheel engaging means, each for engaging a wheel of a skateboard, said device being operable to restrain the wheels against rotation relative to the skateboard.

Abstract: A bicycle sliding dropout comprising a splitting body and a slider slidably engaging the splitting body. The splitting body comprises an inner body and an outer body, the inner and outer bodies being configured to abut each other vertically and matingly engage via a mechanical interface.

Abstract: A bicycle sliding dropout comprises a slider, the slider comprising an axle receptacle. A body is configured for attachment to a bicycle frame. The body and the slider are configured for slidable engagement relative to one another when operatively associated so that the slider may slide first and second opposite directions relative to the body. The body and the slider further comprise cooperating structures selectively limiting the slidable movement of the slider in a first direction and cooperating structures selectively limiting the slidable movement of the slider in a second direction.

Abstract: A bicycle comprising a front triangle and a rear wheel having a rear wheel axis, a rear wheel suspension system further comprising a link further comprising a first pivotal axis for connection to said front triangle and a second pivotal axis for connection to a rear wheel swingarm, wherein the distance from said second pivotal axis to a first vertical plane decreases during a first portion of suspension compression and increases during a second portion of suspension compression; and wherein said first vertical plane is defined as a plane which is perpendicular to the ground and offset in the direction of the rear wheel with respect to the first and second pivotal axis. During the first portion of suspension compression and during the second portion of suspension compression the front triangle remains stationary with respect to the first vertical plane.

Abstract: The invention relates to suspension systems comprising, in certain embodiments, a pivoting means concentric to a wheel rotation axis so that braking forces can be controlled by placement of an instant force center, and so that acceleration forces can be controlled by a swinging wheel link.

Abstract: This application relates to rear suspension system for bicycles, such as freeride, downhill and trail-style mountain bikes. The suspension system includes a rear suspension for coupling the rear wheel of the bicycle to the bicycle frame, a rear shock absorber disposed entirely in front of the seat tube of the frame and a linkage for operatively coupling the rear suspension to the rear shock absorber. The linkage intersects the longitudinal axis of the seat tube for transmitting rear suspension forces around the seat tube to the rear shock absorber. The seat tube is preferably continuous and is disposed so that the bicycle seat is adjustable over a full range of seat positions. The seat tube orientation ensures that the seat is movable between optimum biomechanical positions for both uphill pedaling and aggressive downhill freeriding.

Abstract: A swing-arm-type suspension device for a vehicle transmit rolling from a vehicle body frame side to a rear wheel side quickly. In a swing-arm-type suspension device for a motorcycle, a swing arm is mounted swingably on a pivot shaft provided on a vehicle body frame side, to be more specific, a power unit. One end of a cushion unit is mounted on the swing arm. Another end of the cushion unit is mounted on the swing arm and the power unit by way of a cushion support link mechanism. A rear wheel is supported on an end portion of the swing arm, between a cross pipe that extends between left and right seat rails and the swing arm. A rolling support link mechanism transmits rolling of a vehicle body in the lateral direction to the swing arm from the seat rails on the vehicle-body-frame side.

Abstract: A damper for a bicycle having a primary unit and a remote unit that is substantially entirely outside of the primary unit. The primary unit includes a damper tube, a spring chamber, and a piston rod that supports a main piston. The main piston is movable within the damper chamber of the primary unit. The main piston and the damper tube at least partially define a compression chamber. The remote unit comprises a remote fluid chamber, and an inertial valve within the remote unit. The inertial valve is preferably responsive to terrain-induced forces and preferably not responsive to rider-induced forces when the shock absorber is assembled to the bicycle. The shock absorber forms a flow path separated from the piston rod that connects the remote fluid chamber and the compression chamber of the damper tube.

Abstract: Described are dropout assemblies for bicycles, which include a receiver and a dropout. The dropout assemblies can allow a single bicycle frame to be compatible with various drivetrains, wheels and other components and accessories. The receiver may include inner and outer mounting surfaces on which a dropout may be mounted. The dropout may include first and second mounting surfaces formed to be mounted on the inner or outer mounting surfaces of the receiver. The axle spacing may be adjusted by mounting of either the first or second surface of the dropout on the inner or outer surface of the receiver.

Abstract: A saddle-riding type vehicle includes a vehicle body, a pivot frame that supports a swing arm for rear wheel suspension, and a rear master cylinder disposed rearwardly of the pivot frame. A reservoir tank supplies hydraulic fluid to the rear master cylinder, and the reservoir tank is disposed between the pivot frame and the rear master cylinder. A portion of the swing arm, adjacent to the reservoir tank, is configured with a concave recess formed therein extending inwardly towards a longitudinal center line of the vehicle body. The reservoir tank is situated closer to a vehicle body inner side, and is deeper in the recess than the rear master cylinder.

Abstract: A gear shift pertaining to a hub of a wheel with a quick lock. The hub has a gear which is supported round a shaft with an outer end and an inner end. The inner end of the shaft is suspended via a suspension device on a vehicle. The quick lock includes a rod which runs in a cylindrical hole which is concentric within and with the shaft and a catch which locks the wheel with the shaft to the suspension device. The gear shift includes the shaft, the rod and a control, all so adapted that the rod has a neutral position relative to the shaft and wherein a movement, relative to the shaft, of the rod from the neutral position in a direction from the outer end of the shaft towards the inner end of the shaft disengages the catch so that the wheel together with the shaft can be locked to and released from the suspension device.

Abstract: A rear wheel suspension system for a two-wheeled vehicle is provided. The suspension system includes a rear frame pivotally connected to a main frame by at least an upper linkage and a lower linkage. The linkages are positioned such that the pivotal connection between the rear frame and the lower linkage is forward of the pivotal connection between the main frame and the lower linkage. Further, the rear wheel suspension system includes a biasing member such as a spring or shock absorber which allows the suspension to absorb impacts resulting from obstacles or irregularities in the surface of a terrain.

Abstract: An assembly for a motorized vehicle is disclosed which includes a frame, a power source mounted to the frame, and a transmission connected to the power source. The assembly also includes a swing arm attached to the frame at a pivot point located between the power source and the transmission. The swing arm enables a rear wheel of the vehicle to move vertically relative to the frame. The assembly can also include a suspension system for cushioning the ride of the motorized vehicle and a safety mechanism which has to be manually activated before the vehicle can vertically move from a first, riding position to a second, parked position.

Abstract: A rear wheel suspension for a motorcycle can sufficiently ensure the stroke of a rear cushion and can enhance traveling performance of a vehicle by lowering the gravity center of the vehicle. A swing arm includes an upper arm swingably connecting a body frame with the upper portion of a power transmission portion. A lower arm swingably connects the body frame with the lower portion of the power transmission portion. The axial center of the upper end support portion of a rear cushion is swingably supported by the upper arm at a position forward of the axial center of the support portion. The axial center of the lower support portion of the rear cushion can swingably be supported by the lower arm at a position rearward of the axial center of the support portion swingably supporting the lower arm and the body frame with respect to the vehicle.

Abstract: The invention relates to suspension systems comprising, in certain embodiments, a pivoting means concentric to a wheel rotation axis so that braking forces can be controlled by placement of an instant force center, and so that acceleration forces can be controlled by a swinging wheel link.

Abstract: A shock absorber includes a tube and a piston rod carrying a piston. The piston is configured for reciprocal movement within the tube. A floating piston, or other type of accumulator, is configured to move to accommodate fluid displaced due to successive portions of the piston rod entering the tube during compression of the shock absorber. The shock absorber includes a valve mechanism that utilizes the movement of the floating piston to move the valve between a first and second position, which preferably are open and closed positions.

Abstract: A powered vehicle is disclosed including a chassis and a plurality of wheels. At least one of the wheels is coupled to the chassis with an axle that is coupled to the chassis with a clip.

Abstract: A motorcycle includes a rear swing arm which has upper and lower arms and an arm body. The upper and lower arms are vertically swingably attached to either a body frame or an engine via pivot shafts that are disposed in vertically spaced relation to each other and extend parallel to each other toward a rear wheel. The arm body is swingably connected to a rear end of the upper and lower arms via support shafts for supporting the rear wheel.

Abstract: An apparatus capable of temporarily limiting travel of the rear suspension system of a motorcycle for the purpose of obtaining better traction when accelerating. The apparatus includes a device having a first base secured to at least one frame member of the motorcycle at a location above a rear suspension member of the motorcycle, and a second base secured to the rear suspension member at a location in proximity to the first base. A post is pivotally mounted to the first base to have first and second positions. In the first position, the post extends toward the second base an engages a retention feature in the second base to prevent movement of the rear suspension member and frame member toward each other. In the second position, the post is disengaged from the retention feature and pivoted away from the second base to permit movement of the rear suspension member and frame member toward each other.

Abstract: A bicycle shock absorber and methods for differentiating between rider-induced forces and terrain-induced forces includes a first fluid chamber having fluid contained therein, a piston for compressing the fluid within the fluid chamber, a second fluid chamber coupled to the first fluid chamber by a fluid communication hose, and an inertial valve disposed within the second fluid chamber. The inertial valve opens in response to terrain-induced forces and provides communication of fluid compressed by the piston from the first fluid chamber to the second fluid chamber. The inertial valve does not open in response to rider-induced forces.

Abstract: A swing arm suspension for reducing the number of parts to thereby reduce the number of man-hours for assembly, the weight and the cost. The swing arm suspension includes a pivot plate provided with a pivot shaft, a swing arm having a rear end portion supporting a rear wheel that is swingably mounted at a front end portion to the pivot shaft and a shock absorber that is mounted at an upper end portion to the swing arm and connected at a lower end portion through a link mechanism to a portion of the pivot plate at a lower level than the pivot shaft. An exposing portion is provided for exposing a shock absorber arrangement space to an upper space above the swing arm. At least one of a subtank and an adjuster as functional components of the shock absorber is located in the exposing portion.

Abstract: A saddle type vehicle includes a down tube extending downward from a head pipe for supporting a front fork, a rear wheel pivot unit provided on the down tube, and a rear wheel suspension device for supporting a rear wheel of the vehicle such that the rear wheel can pivot substantially upward and downward around the rear wheel pivot unit. The rear wheel pivot unit is disposed before an engine in the advancing direction of the vehicle. The engine is attached to the rear wheel suspension device such that the engine can pivot with the rear wheel suspension device.

Abstract: A swing arm support structure is provided in a motorcycle, in which first and second support arm portions are provided on a front portion of a swing arm. The support arm portions are pivotally supported by a power unit through first and second pivot shafts, so that rigidity and strength of the paired support arm portions is ensured. A flange is formed on the first pivot shaft, which extends at least partially up to an outer edge of a power unit case and projects radially outwardly from an end portion of the first pivot shaft adjacent the case. The flange portion is removably attached to the case. An outer end of an output shaft extends through and is supported by the first pivot shaft, and this outer end projects outwards of the first support arm portion. A drive gear is fixed to the outer end portion of the output shaft.

Abstract: The frame includes at its rear portion two bases (12, 13) extending substantially horizontally rearwardly so as to define between them a space for the reception of a rear wheel, and two stays (14, 15) extending obliquely toward one respective end of the bases (12, 13) and being connected thereto at an acute angle by connection elements, a pair of recesses for a rear wheel axle being disposed substantially at the intersection of the stays (14, 15) with the bases (12, 13) . Each recess of the pair of recesses has a first notch with a semicircular bottom (23) provided at one flattened end of a base and a second notch with a semicircular bottom (24) provided at a flattened end of a stay and disposed facing the first notch (23) such that the semicircular bottoms will be aligned with each other.

Abstract: A rear wheel suspension system for a two-wheeled vehicle is provided. The suspension system includes a rear frame pivotally connected to a main frame by at least an upper linkage and a lower linkage. The linkages are positioned such that the pivotal connection between the rear frame and the lower linkage is forward of the pivotal connection between the main frame and the lower linkage. Further, the rear wheel suspension system includes a biasing member such as a spring or shock absorber which allows the suspension to absorb impacts resulting from obstacles or irregularities in the surface of a terrain.

Abstract: This application relates to rear suspension system for bicycles, such as freeride, downhill and trail-style mountain bikes. The suspension system includes a rear suspension for coupling the rear wheel of the bicycle to the bicycle frame, a rear shock absorber disposed entirely in front of the seat tube of the frame and a linkage for operatively coupling the rear suspension to the rear shock absorber. The linkage intersects the longitudinal axis of the seat tube for transmitting rear suspension forces around the seat tube to the rear shock absorber. The seat tube is preferably continuous and is disposed so that the bicycle seat is adjustable over a full range of seat positions. The seat tube orientation ensures that the seat is movable between optimum biomechanical positions for both uphill pedaling and aggressive downhill freeriding.

Abstract: A structure for supporting a swing arm in a motorcycle is provided in which a power unit swingably supports a front portion of the swing arm via a first pivot of a cylindrical shape that is coaxial with an output shaft of the power unit and a second pivot that is coaxial with the first pivot. The number of parts used are reduced and the removal and installation of the swing arm is facilitated. An output shaft, an outer end portion of which projects outwardly of a swing arm, is connected to a final transmission member of a reduction transmission and is capable of removal or insertion in an axial direction, while being incapable of relative rotation about an axis. A first pivot is removably mounted on a power unit. A second pivot is removably secured to the power unit PA or the swing arm.

Abstract: A rear suspension for a vehicle such as a bicycle or motorcycle that includes a frame, a swinging arm integral with the frame carrying the axle of a drive wheel hub and a shock absorber whose ends are secured to the frame and to the swinging arm, the swinging arm being secured to said frame by at least two articulation means so that the swinging arm pivots about an “instantaneous centre of rotation” that is movable when the hub is displaced on either side of its reference position corresponding to the position of the hub axle when the vehicle is in a static equilibrium position, characterized in that the instantaneous centre of rotation is displaced upwards along a parabolic path, the asymptote of which is oriented towards the rear free end of the swinging arm carrying the axle of the hub when said hub is displaced above its reference position.

Abstract: A rear wheel suspension system for a motorcycle has a swing arm with a pivot axis at a forward end and a wheel axis at a rear end. A wheel axle is slide mounted in a direction of travel substantially parallel to the motorcycle fork. A pair of springs mounted within the swing arm biases the wheel axle in forward neutral position and pulls the wheel axle to forward neutral position when the wheel is forced backward.

Abstract: The invention provides a suspension apparatus of a vehicle comprising a base end portion of a swing arm pivotally attached to a vehicle body so as to freely oscillate, and a wheel which is rotatably supported to a leading end portion of the swing arm. A first link is pivotally attached to a portion between the base end portion and the leading end portion of the swing arm. A second link is pivotally attached to a position which is below a pivot point to which the base end portion of the swing arm is pivotally attached in the vehicle body, and the first link and the second link are pivotally attached. One end of a cushion unit is pivotally attached to the vehicle body. Another end of the cushion unit is pivotally attached to one of the first link and the second link, in which the first link or the second link comprises an expandable link. The expandable link is energized in a contracting direction.

Abstract: A progressive rear suspension linkage is used in the rear suspension of an ATV to aid in ride quality and safety by changing leverage ratio thru the travel of the rear suspension. The rear shock attaches to it as well as to the frame. The linkage system attaches to the frame at one end and to the rear suspension arm at the other end and changes leverage as the mounting point on the frame and the rear suspension arm come closer together or further apart as the rear suspension arms moves thru its travel. This in turn lets some linkages move in a scissors type movement with the rear shock bolted to it at a given point. This invention provides an improvement to the OEM designs, making for improved handling and safer control of ATVs.

Abstract: A motorcycle having an improved rear suspension in which the shock leverage rate is decoupled from the spring leverage rate. The springs are coupled directly between the swingarm and the frame, while the shock is coupled to the swingarm and coupled to the engine by a linkage. The rear suspension has a substantially linear spring leverage rate, and a different shock leverage rate which is determined by the linkage and is not necessarily linear. The springs are coupled to the swingarm by a spring base which threads into a ride height adjuster cup which is coupled to the swingarm and which can be rotated to raise and lower the ride height, and a preload cup which is coupled to the frame and which can be rotated to increase and decrease the preload on the spring.

Abstract: A wheeled vehicle includes a body frame, at least one wheel and an arm unit. A first end of the arm unit is supported by the frame body for pivotal movement about a pivot axis that extends generally horizontally and transversely. A second end of the arm unit rotatably carries the wheel. The arm unit defines an inner cavity that has first and second inner surfaces spaced apart from each other. The arm unit has a reinforcement that extends between the first and second inner surfaces.

Abstract: A structural member (38, 40) is designed to have a first portion having a first composite layup, a second portion having a second composite layup, and at least one center portion having at least a third composite layup such that it can flex near a desired point of the structural member. The structural member may be used as a chain stay (26) in a bicycle frame (10). The chain stays are designed to have a geometry that will allow for flexing or bending at or in the vicinity of a desired point. They may be pre-loaded for flex in both a positive and negative direction. The chain stays are designed having a varying cross sectional area. The bending or flexing location of the chain stays has a narrower height from the side view than the ends of the chain stay allowing the chain stay to flex. Additionally, the bending or flexing location has a wider width from the top view than the ends of the chain stay for additional torsional and lateral stiffness.

Abstract: A rear single-sided swingarm suspension for a motorcycle includes a single-sided swingarm that has an axle bearing assembly pivotably connected to the rearward end thereof for swinging motion in a plane parallel to the plane of travel of the swingarm. A cantilevered wheel axle is journalled in the axle bearing assembly and is affixed to the rear wheel. A control arm, which is shorter than the swingarm, extends generally parallel to the swingarm and is pivotably connected to the motorcycle frame at a point rearward of the forward end of the swingarm. The axle bearing assembly also is pivotably attached to the rear end of the control arm. The wheel axle is journalled in the axle bearing assembly at a point rearward of the rear end of the swing arm and on the opposite side of the swingarm from the control arm.

Abstract: The present invention includes a base frame or hitch receiver which can be attached to the under surface of a pulling vehicle. A hitch frame is pivotally mounted to the base frame for pivotal movement about a horizontal axis. An air bag is positioned between the base frame and the hitch frame and is adapted to collapse in response to downward movement of the forward end of the hitch frame. This collapsing of the air bag causes the air within to be compressed so that it resist downward movement of the forward end of the hitch bar.