Rear shock absorber

The two rear BOGE shock absorbers are complementary of the torsion bar. They are piston operated, double-acting hydraulic type. The body of the unit is bored to take two pistons, one on either side of a rocker arm which is held centrally between them.

The rocker arm pivots about a shaft provided externally with a lever arm. Vertical movement of the car axle relative to the chassis, causes the lever arm to swing through an arc thus rotating the rocker shaft and arm; the latter pushes one piston towards one end of the cylinder and withdraws the other piston from the opposite end of the cylinder.

Since both ends of the cylinder are closed, a high pressure is built up in the oil at one end of the unit whilst a decrease in pressure occurs at the other end. A non- return recuperation valve situated in the piston head allows oil to pass from a reservoir to the low pressure end, thus keeping this normal. This leaves the oil pressure on the one piston head opposing lever arm move- ment. In order to spread the absorption of the shock, a leakage path is provided from each end of the cylinder to the reservoir, thus reducing the rate at which the pressure is built up. Finally, blow-off valves are fitted which limit the pressure reached, thereby controlling the resistance offered by the shock absorber.

When the lever arm is moved in the opposite direction, the function of the two pistons are interchanged. As is frequently the custom with German shock absorbers, the units are arranged to give a low resistance in the direction of the initial shock and a high resistance in the reverse direction to dissipate the energy stored in the springs.

The following pictures show a shock absorber being restored. The spinnaker seal has been changed, same for the copper ring.