Abstract: A damping force control type hydraulic shock absorber includes a cylinder having a hydraulic fluid sealed therein. A piston is slidably fitted in the cylinder to divide the inside of the cylinder into two chambers. A main hydraulic fluid passage provides communication between the two chambers and has a damping force generating mechanism. A bypass passage also provides communication between the two chambers. A cylindrical guide member is provided in the bypass passage to provide communication between two portions of the bypass passage which lead to the two chambers, respectively, through ports provided in the side wall of the guide member. A cylindrical shutter is rotatably fitted in the guide member. The shutter has openings capable of aligning with the ports. The ports and the openings cooperate to provide a damping force which changes generally linearly as the shutter rotates.

Abstract: A cylinder (7) having a hydraulic fluid sealed therein is fitted with a piston (8) having a piston rod (9) connected thereto. The piston rod (9) is provided with a bypass passage (B) (generating relatively small damping force). The passage area of the bypass passage (B) is controlled by varying the area of orifices formed by guide ports (21 and 22) and shutter ports (24 and 25) by rotating a shutter (23), thereby changing damping force characteristics. Auxiliary ports (34 and 35) are provided to open into the guide ports (21 and 22), respectively.

Abstract: A magnetic recording medium is disclosed. The medium is comprised of a non-magnetic support base having a surface with a center line average loughness (Ra) of not more then 0.035 .mu.m, having coated thereon a magnetic layer. The magnetic layer is comprised of a ferromagnetic powder, a fatty acid ester and two types of carbon black dispersed in a binder. The first type of carbon black has an average primary particles sizes of 10 to 30 m.mu.. The second type of carbon black has an average primary particle size of 60 to 120 m.mu.. The first type of carbon black and second type of carbon black are present in a mixing weight ratio in the range of 60/40 to 95/5. The magnetic recording medium has excellent electromagnetic properties and provides a tape having good running property and durability.