A seat cushion is swingable about an axis A with respect to a seat cushion support frame that is a part of a main frame. A cushion return spring that is a flat spring is disposed between the seat cushion and the seat cushion support frame so that an elastic force of the cushion return spring returns the seat cushion to a neutral position. A pair of clamp rollers that clamps the cushion return spring is disposed. The clamp rollers are movable along a longitudinal axis of the cushion return spring. Changing of a clamping position by moving the clamp rollers changes an effective length of the cushion return spring. In this way, a swingable range of the seat cushion and a force to return the seat cushion to the neutral position are changed.

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.

A gyro seat includes: a seat body comprising a seat cushion and a seat back coupled to the seat cushion; and a seat gyroscope mounted to the seat body, the seat gyroscope compensating a movement of the seat body by control of first, second and third axes, where the first axis corresponds to a yaw of the seat body as a z axis of an xyz coordinate system, the second axis corresponds to a pitch of the seat body as an x axis of the xyz coordinate system, and the third axis corresponds to a roll of the seat body as a y axis of the xyz coordinate system.

A vehicle seat includes a lock-to-neutral-position mechanism that locks a seat cushion at a neutral position, and an immediate lock mechanism that locks the seat cushion immediately at a current position when locking is required. A steering sensor senses a steering angle and a steering angular velocity. The immediate lock mechanism performs the locking when the steering angle is large, whereas the lock-to-neutral-position mechanism performs the locking when the steering velocity is high. When the steering wheel is at the neutral position, the locking by the immediate lock mechanism is released and the locking is switched over to the lock-to-neutral-position mechanism that is in a lock ready state.

A vehicle seat includes a lock-to-neutral-position mechanism that locks a seat cushion at a neutral position, and an immediate lock mechanism that locks the seat cushion immediately at a current position when locking is required. A steering sensor senses a steering angle and a steering angular velocity. The immediate lock mechanism performs the locking when the steering angle is large, whereas the lock-to-neutral-position mechanism performs the locking when the steering velocity is high. When the steering wheel is at the neutral position, the locking by the immediate lock mechanism is released and the locking is switched over to the lock-to-neutral-position mechanism that is in a lock ready state.

A vehicle seat having a vehicle seat underbody, comprising: a base plate; a side horizontal suspension; a rolling suspension comprising a rod element rotatably mounted with respect to the side horizontal suspension; a scissors-type frame having a first swing and a second swing, wherein the first swing is connected by a first slide element to the rod element and the second swing is connected by a second slide element to the rod element and the first swing is connected to the first slide element and the second swing is connected to the second slide element; a first element carrier; a lengthwise horizontal suspension; and a first spring element, which is connected on the one hand to the first element carrier and on the other hand to the base plate or one of the swings.

A locking block is fixed with respect to a seat cushion. A locking pin which can advance and retract relative to the locking block is provided on a main frame side. A V groove shape receptacle is formed on the locking block. When the locking pin is advanced into the receptacle portion, the locking pin is guided by a receiving inclined surface of the receptacle portion forming the V-shape groove, and advances to a bottom of the receptacle portion. With this process, the locking block moves in a rotational direction B, and when the locking pin engages the bottom, the seat cushion is fixed.

A passive self-adjusting seat assembly for a lawn maintenance vehicle having a frame. The passive self-adjusting seat assembly includes a base, a guide assembly attached to the base, and a platform assembly that is selectively movable or slidable relative to the guide assembly in order to maintain an operator in an upright or substantially vertical orientation as the lawn maintenance vehicle traverses uneven or sloped ground. The seat assembly further including a locking assembly for selectively locking the sliding or movement of the platform assembly relative to the guide assembly.

A passive self-adjusting seat assembly for a lawn maintenance vehicle having a frame. The passive self-adjusting seat assembly includes a base, a guide assembly attached to the base, and a platform assembly that is selectively movable or slidable relative to the guide assembly in order to maintain an operator in an upright or substantially vertical orientation as the lawn maintenance vehicle traverses uneven or sloped ground. The seat assembly further including a locking assembly for selectively locking the sliding or movement of the platform assembly relative to the guide assembly.

System and methods 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; an occupant cell one of coupled to and defined by the chassis structure; and one or more of a seat assembly configured to receive the occupant in a seated position and a standing platform assembly configured to receive the occupant in a standing position disposed within the occupant cell; wherein the one or more of the seat assembly and the standing platform assembly is/are configured to pivot one or more of: laterally at a longitudinal pivot point with respect to the chassis and travel plane; and longitudinally at a transverse pivot point with respect to the chassis and travel plane.