A hydraulic clutch master cylinder is shown in Figure 35-14. Its pushrod moves the piston and primary cup to create hydraulic pressure. The snap ring restricts the travel of the piston. The secondary cup at the snap ring end of the piston stops hydraulic fluid from dripping into the passenger compartment. The piston return spring holds the primary cup and piston in the fully released position. Hydraulic fluid is stored in the reservoir on top of the master cylinder housing.