Patent attributes
A displaceable spring seat (2) supporting one end of a vehicle suspension spring (S) is supported by a fluid pressure of an operation chamber (J). A screw pump (P) supplying a working fluid to the operation chamber (J) includes a pump chamber (L) defined within a cylinder (10) by a piston (11, a nut (13) formed integrally with the piston (11), and a screw shaft (14) screwed into the nut (13). A guide member (16) fixed to the cylinder (10) is fitted onto an outer circumference of the nut (13) or the piston (11) such that when the screw shaft (14) is driven to rotate, the piston (11) is fed via the nut (13). The guide member (16) formed from a non-metallic, low-friction material, reduces a driving resistance of the piston (11) and improves a durability of a screw portion between the nut (13) and the screw shaft (14).
