In a cushion mechanism of a gas cylinder, when the pressure of a gas in a first pressure chamber is less than or equal to a prescribed pressure, a valve body cuts off communication between the upstream side and downstream side of a discharge flow passage by mean of the biasing force of a spring member. In addition, when the pressure of the gas exceeds the prescribed pressure, the valve body is displaced to the downstream side of the discharge flow passage against the biasing force, thereby enabling communication between the upstream side and the downstream side of the discharge flow passage.

A spool valve for controlling the flow of a fluid into a reciprocating piston cylinder. A spool is slideably inserted into an outer casing, the spool valve having a first and a second non-waisted end portions and having a waisted middle portion. The casing has an intake port and output port for fluids entering and exiting the casing. A first non-waisted end portion covers the intake port during a first valve-closed event as the spool slides in one direction within the casing. The waisted middle portion is sufficiently wide to uncover both the intake port and the output port during a valve-open event as the spool slides in one direction within the casing. A second non-waisted end portion covers the output port during a second valve-closed event as the spool slides in the same one direction within the casing.

A hydraulic assembly includes a barrel having a head port disposed proximate an end of the barrel, a piston assembly disposed within the barrel and movable relative thereto, the piston assembly including a bore terminating at a back wall, the bore defining a longitudinal axis, and a plunger at least partially received within the bore and translatable along the longitudinal axis. The plunger includes a main body having an end facing the head port, a shoulder extending radially-outwardly from the main body, and a passageway extending through the main body. A spring is disposed in a first region defined between the shoulder and the back wall, the spring configured to exert a biasing force on the shoulder.

A steering system for an articulated truck. The articulated truck is formed of a tractor and a trailer and an articulation joint. The steering system includes a hydraulic cylinder, with a cylinder barrel and a piston. The steering system provides for changes in angle between the tractor and the trailer. The hydraulic cylinder includes a snubbing tube projecting into the cylinder barrel. A hydraulic fluid passage opens into the cylinder barrel within the snubbing tube. The snubbing tube includes a main slot and a plurality of channels each extending between an interior and an exterior of the snubbing tube. The plurality of channels have a cross sectional area smaller than a cross sectional area of the main slot. When the articulated truck is steered, the piston moves in the cylinder barrel and the snubbing tube dampens the movement to prevent forces generated by the piston damaging the articulated truck.

Cushion holes are provided in cover members, tubular cushion rings are provided on a piston and a piston rod so as to be insertable into and withdrawable from the cushion holes as the piston moves, cushion packings capable of slidably contacting the outer circumference of the cushion rings are mounted to be movable in an axial direction, in mounting grooves formed on inner walls of the cover members constituting the cushion holes, the cushion packings each include a plurality of protrusions extending from the outer circumferential surface to the side surface near the piston and disposed circumferentially alongside one another, and cushioning grooves that extend in parallel with the axis of the cushion rings and whose cross-sectional area changes are formed on the outer circumferential surface of the cushion rings.

A pneumatic cylinder includes a cylinder body, a piston assembly, a connecting rod, and at least one pressure-relief valve. The cylinder body is formed with a cylinder chamber, and has an exterior disposed with at least one inlet-outlet passage and at least one pressure-relief opening, wherein the inlet-outlet passage is connected to the cylinder chamber. The piston assembly is contained within the cylinder chamber. The connecting rod is connected to the piston assembly, and protrudes out from the cylinder body. The pressure-relief valve is disposed in the pressure-relief opening, and has two ends connected to an outside of the pneumatic cylinder and the cylinder chamber respectively. When a gas pressure within the cylinder chamber is greater than a threshold value, the pressure-relief valve works to allow the cylinder chamber connecting to the outside for pressure relief.

A pair of air cylinders that cause a valve plate to perform an opening/closing operation each include a head-side air cushion mechanism and a rod-side air cushion mechanism. Each head-side air cushion mechanism includes a head-side communication path and a head-side restricting flow path that connect a head-side pressure chamber and a head-side main flow path in parallel, and a blocking mechanism that blocks the head-side communication path when a piston approaches a retreat stroke end, and each rod-side air cushion mechanism includes a rod-side communication path and a rod-side restricting flow path that connect a rod-side pressure chamber and a rod-side main flow path in parallel, and a blocking mechanism that blocks the rod-side communication path when the piston approaches an advance stroke end.

A pin assembly for a piston block of a hydraulic cylinder includes a pin that is axially engaged with the piston block. The pin assembly also includes a floating bush that is spaced apart from the pin to receive a sleeve therebetween. The floating bush is also configured to exhibit axial and radial play in its movement relative to the sleeve. The axial and radial play in the movement of the floating bush allows the floating bush to align with a cap port of the cylinder housing prior to entering the cap port of the cylinder housing.

In a piston and cylinder device, such as a hydraulic cylinder, potential or kinetic energy of the piston just before reaching the cylinder head at the end of a stroke can be mitigated using a rod spud/cushion sleeve arrangement where the rod spud and cushion sleeve comprise complementary continuously and gradually tapered portions forming an annular orifice having a cross-sectional area that dynamically, continuously and gradually decreases as an external tapered portion of the rod spud moves through an internal tapered portion of the cushion sleeve to the end of the piston stroke.

Cushion holes are provided in cover members, tubular cushion rings are provided on a piston and a piston rod so as to be insertable into and withdrawable from the cushion holes as the piston moves, cushion packings capable of slidably contacting the outer circumference of the cushion rings are mounted to be movable in an axial direction, in mounting grooves formed on inner walls of the cover members constituting the cushion holes, the cushion packings each include a plurality of protrusions extending from the outer circumferential surface to the side surface near the piston and disposed circumferentially alongside one another, and cushioning grooves that extend in parallel with the axis of the cushion rings and whose cross-sectional area changes are formed on the outer circumferential surface of the cushion rings.