Pressure-sensitive vales are incorporated within a dampening system to permit user-adjustable tuning of a shock absorber. In one embodiment, a pressure-sensitive valve includes an isolated gas chamber having a pressure therein that is settable by a user.

Methods and systems for vehicle suspension are provided. A leveling manifold includes, in one example, a plurality of electrically-activated valves arranged between, on a first end, a rod-side and a piston-side of one or more hydraulic cylinders, and on a second end, a pressure source and a tank, wherein the plurality of electrically-activated valves include a first valve, a second valve, a third valve, and a fourth valve. The leveling manifold further includes a first flow path extending through the first and second valves and from the rod-side to the second end and a second flow path extending through the third and fourth valves and from the piston-side to the second end, the leveling manifold is designed to manage operation of the first, second, third, and/or fourth valves to independently adjust a position and a stiffness of the one or more hydraulic cylinders.

Methods and systems for vehicle suspension are provided. A leveling manifold includes, in one example, a plurality of electrically-activated valves arranged between, on a first end, a rod-side and a piston-side of one or more hydraulic cylinders, and on a second end, a pressure source and a tank, wherein the plurality of electrically-activated valves include a first valve, a second valve, a third valve, and a fourth valve. The leveling manifold further includes a first flow path extending through the first and second valves and from the rod-side to the second end and a second flow path extending through the third and fourth valves and from the piston-side to the second end, the leveling manifold is designed to manage operation of the first, second, third, and/or fourth valves to independently adjust a position and a stiffness of the one or more hydraulic cylinders.

A flow path control device according to one embodiment includes a first valve, a unit main body and a control valve. The unit main body has an accommodation portion, a first radial communication hole and a side recess portion. The accommodation portion is recessed from a chamber accommodating the oil to cause the first valve to close the first radial communication hole. The side recess portion is recessed from the chamber so as to be continuous to the accommodation portion and not to be continuous to the first radial communication hole. The control valve is movable in the accommodation portion of the unit main body between a position at which a groove of the control valve communicates with the side recess portion and the first radial communication hole and a position at which the groove does not communicate with them.

A flow path control device according to one embodiment includes a first valve, a unit main body and a control valve. The unit main body has an accommodation portion, a first radial communication hole and a side recess portion. The accommodation portion is recessed from a chamber accommodating the oil to cause the first valve to close the first radial communication hole. The side recess portion is recessed from the chamber so as to be continuous to the accommodation portion and not to be continuous to the first radial communication hole. The control valve is movable in the accommodation portion of the unit main body between a position at which a groove of the control valve communicates with the side recess portion and the first radial communication hole and a position at which the groove does not communicate with them.

A flow path control device according to one embodiment includes a first valve which transitions between a closed state where a first flow is closed and an open state where the first flow path is open by moving toward an space from the closed state. The first valve is formed with an axial through-hole that communicates with the first flow path and the space. A pressure-receiving area of the first valve against a jack chamber is smaller than that against the space. Further, a second valve is provided in the space on a second flow path so as to transition between a first state where the axial through-hole is closed and an inflow path oriented toward the space from the jack chamber is open and a second state where it is closed and the axial through-hole is open.

A flow path control device according to one embodiment includes a first valve which transitions between a closed state where a first flow is closed and an open state where the first flow path is open by moving toward an space from the closed state. The first valve is formed with an axial through-hole that communicates with the first flow path and the space. A pressure-receiving area of the first valve against a jack chamber is smaller than that against the space. Further, a second valve is provided in the space on a second flow path so as to transition between a first state where the axial through-hole is closed and an inflow path oriented toward the space from the jack chamber is open and a second state where it is closed and the axial through-hole is open.

A vehicle height adjustment apparatus according to one embodiment include a spring, a spring-length changing unit, a first valve, a control valve and a second valve. The spring-length changing unit changes a length of the spring in accordance with an amount of oil in a jack chamber that accommodates the oil. The first valve opens and closes a first communication path in which the oil supplied from a pump is oriented toward a reservoir chamber that stores the oil. The control valve opens and closes a discharge flow path oriented toward the reservoir chamber from a chamber that accommodates the oil to close the first valve. The second valve opens and closes a second communication path in which the oil supplied from the pump is oriented toward the jack chamber when the first valve is closed.

A vehicle height adjustment apparatus according to one embodiment include a spring, a spring-length changing unit, a first valve, a control valve and a second valve. The spring-length changing unit changes a length of the spring in accordance with an amount of oil in a jack chamber that accommodates the oil. The first valve opens and closes a first communication path in which the oil supplied from a pump is oriented toward a reservoir chamber that stores the oil. The control valve opens and closes a discharge flow path oriented toward the reservoir chamber from a chamber that accommodates the oil to close the first valve. The second valve opens and closes a second communication path in which the oil supplied from the pump is oriented toward the jack chamber when the first valve is closed.

An air spring with damping characteristics for a suspension assembly of a heavy-duty vehicle includes a bellows chamber, a piston chamber and an asymmetrical orifice. The asymmetrical orifice is in fluid communication with the bellows chamber and the piston chamber of the air spring. The asymmetrical orifice provides asymmetrical damping characteristics to the air spring of the heavy-duty vehicle.