Neuman, Williams, Anderson & Olson
Brake actuators
 Brake actuators are provided which use pistons for both auxiliary and service functions, the auxiliary piston being operative to compress a spring in response to fluid source pressure and the service piston being operative to develop throughout its movement a brake operating force which is uniformly proportionate to service fluid pressure. Two cup-shaped housing members have rim portions secured together. One of such cup-shaped members and a metal sleeve define cylindrical surfaces for co-action with the pistons, the metal sleeve being disposed within a resilient sleeve which is disposed at least partly within the other of the cup-shaped members. The service piston is located in front of the auxiliary piston and coacts with the cylindrical surface of the metal sleeve. A resilient boot is disposed between the service piston and a forward end wall, around an actuating rod having a rearward end in engagement with the service piston. 
The Echlin Manufacturing Company
B
B60T
inventional
Sergio
Campanini