Abstract: An oil seal or fluid seal for providing a seal between a cylinder and a piston rod is provided. The oil seal has an annular seal lip which has on a conical inner circumferential surface thereof a plurality of annular projections which are arranged axially of the seal lip. One of the annular projections which is located more axially outside of the cylinder is larger in the height above the inner circumferential surface than one of the annular projections which is located more axially inside of the cylinder. By this, under a condition where the annular projections which are located more axially inside of the cylinder are subjected to a high pressure within the cylinder, the annular projections which are located more axially inside of the cylinder and the annular projections which are located more axially outside of the cylinder are nearly equal in the contact pressure against the piston rod, thus causing all of the annular projections to deform nearly equally.

Abstract: A piston ring of Teflon (trademark of E.I du Pont de Nemours & Co, Ltd.), i.e., polytetrafluorethylene fiber, is mounted on a piston. The piston ring has an integral portion in the form of a series of axially spaced circumferential projections received in the respective circumferential spaced grooves of the piston. The piston is projected radially and outwardly to abut an axial end of a sleeve portion of the piston ring to limit axial movement of the piston ring.

Abstract: A variable damping characteristics shock absorber includes a piston provided with first and second disc valves. Within a piston, an annular space is defined between the first and second disc valves. The annular space is selectively communicated with upper and lower fluid chambers defined in a shock absorber cylinder tube via a by-pass path. A variable orifice formed by means of a rotary valve is provided in the by-pass path.

Abstract: A shock absorber is provided a piston stroke speed dependent linear variation characteristics of damping force. The shock absorber includes variable orifices in tandem fashion for achieving linear variation characteristics of damping force according to variation of the piston stroke. One of the variable orifices is provided with variation characteristics of flow restriction for a greater variation rate of the damping force in a low piston stroke speed range, and the other is provided variation characteristics of flow restriction for a greater variation rate of the damping force in the intermediate and high piston stroke speed range. The variable orifice may be provided in a piston assembly or in the alternative in a bottom fitting in the case of a double-action type shock absorber.

Abstract: A variable damping force shock absorber has a hollow cylinder, in which is disposed a thrusting piston for defining upper and lower fluid chambers. A fluid path is defined through the piston and a piston rod for establishing fluid communication between the upper and lower fluid chambers. A first flow restrictive orifice is provided in the fluid path which first flow restrictive orifice has variable flow restriction characteristics according to a first variation characteristic in relation to a piston stroke speed. A second flow restrictive orifice is also provided in the fluid path. The second flow restrictive orifice has a variable multitude flow restriction according to a second variation characteristic in relation to the piston stroke speed, which second variation characteristic is so determined as to establish, linear variation of damping force in relation to the piston stroke speed. A communication path is formed for establishing communication between the first and second flow restrictive orifices.

Abstract: A hydraulic damper with a rod guide made by pressing a circular plate is disclosed. This rod guide includes an inner tubular portion defining a bore supporting a piston rod, an outer tubular portion extending in the same direction as the inner tubular portion does, and a flange portion extending radially outwardly from the outer tubular portion. A ring is connected between an inwardly turned axial end portion of an outer tube and the flange portion. An annular sealing element retainer is disposed in the ring. The ring provides a transmission path of a force, thus preventing the sealing element retainer from being subject to the force.

Abstract: A hydraulic shock absorber is provided which includes generally a cylinder assembly to define working and reservoir chambers therewithin, a piston rod, a rod guide member which guides bounding and rebounding strokes of the piston rod, and an oil seal contacting with the piston rod to seal an opening of the cylinder assembly. The rod guide member includes outer and inner supporting sections. The inner supporting section also includes outer and inner wall sections which are coaxially arranged with a preselected interval therebetween. The outer wall section is spaced from an inner wall of the cylinder assembly to provide flexibility to the rod guide in cooperation with the inner wall section.

Abstract: A variable-damping-force shock absorber such that the damping force determined through an orifice selected by an orifice adjuster according to the driver's preference can further automatically be increased during extension for improvement in road-holding ability and decreased during compression for improvement in riding comfort. The shock absorber according to the present invention comprises an annular member formed with an orifice and a disk valve disposed on top of the annular member. During extension, the disk valve is closed for allowing fluid to by-pass through an orifice of the annular member; during compression, the disk valve is opened for additionally allowing fluid to by-pass through the annular member. Further, since the various elements for adjusting the damping force are completely housed within the piston rod, it is possible to increase the stroke of the piston rod.

Abstract: A variable-damping-force shock absorber in which the motor for rotating the orifice adjuster is housed within the cylinder and the orifice-adjuster position sensor for outputting binary coded sensor signals is incorporated. Therefore, it is possible to reduce noise generated from the motor while improving the lifetime of the motor because mud or rain water will not adhere onto the motor and to improve the precision and the response speed in rotating the orifice adjuster because the adjuster can be feedback controlled in digital fashion. Further, since the driven shaft of the motor or the reduction gear is loosely coupled with the orifice adjuster in the axial direction thereof, it is possible to reduce the torque or the size of the motor, because fluid pressure is not directly applied to the driven shaft via the orifice adjuster.