Abstract: An acceleration sensitive shock absorber has a tubular housing and a piston assembly in the housing dividing the housing into an upper chamber and a lower chamber. The piston is connected to the wheel of a vehicle and the housing is connected to the chassis of the vehicle. Fluid can pass between the upper and lower chambers with a restricted flow rate during either extension or compression of the shock absorber. There is a port for providing fluid flow from the lower chamber to the upper chamber during downward acceleration of the wheel. A movable inertial mass in the piston assembly opens the port during downward acceleration of the wheel of the vehicle for increasing flow between the chambers. A pocket beneath the inertial mass applies sufficient pressure to the inertial mass to retain it in a port-open position during fluid flow after acceleration has decreased. An enlarged diameter relief portion inside the inertial mass minimizes inconsistent performance in mass produced shock absorbers.

Abstract: An acceleration sensitive shock absorber has a tubular housing and a piston assembly in the housing dividing the housing into an upper chamber and a lower chamber. The piston is connected to the wheel of a vehicle and the housing is connected to the chassis of the vehicle. Fluid can pass between the upper and lower chambers with a restricted flow rate during either extension or compression of the shock absorber. There is a first port for providing fluid flow from the lower chamber to the upper chamber upon downward acceleration of the wheel. A movable inertia valve in the piston assembly opens the first port when acceleration of the wheel of the vehicle is greater than a predetermined magnitude for increasing flow between the chambers. In addition, there is a first orifice downstream from the first port for creating hydraulic pressure which biases the inertia valve in an open position in response to fluid flow between the chambers.