Tandem type brake power servo booster

A tandem type brake toggle joint, comprising:

• an input shaft;
• a valve body;
• a valve mechanism enclosed within said valve body for opening and closing a passage for a pressurized fluid in response to an axial movement of said input shaft;
• a hub disposed in front of said valve body;
• a push rod having a base end fitted within said hub;
• a front power piston and a rear power piston operated by said fluid pressure from said valve mechanism to transmit a thrust to said push rod;
• first stop means provided on a rear of said hub for preventing any frontward displacement of said hub relative to said valve body;
• a center body surrounding said hub and extending slidably through a center plate;
• and
• second stop means provided at the front end of said hub, said first and second stop means joining said valve body and said center body integrally with each other.

A tandem type brake toggle joint, comprising:

• an input shaft;
• a valve body;
• a valve mechanism enclosed within said valve body for opening and closing a passage for a pressurized fluid in response to an axial movement of said input shaft;
• a hub disposed in front of said valve body and having a base end received in said valve body;
• a valve plunger fitted slidably within said hub;
• a key member extending through said valve body and said hub and engaging said valve plunger, said key member abutting said hub to provide a space between said key and the valve body;
• a push rod having a base end fitted within said hub;
• a front power piston and a rear power piston operable by fluid pressure from said valve mechanism to transmit a thrust to said push rod;
• a surface of said key member facing said push rod being spaced apart from said valve body to form a clearance therebetween to keep said valve body and said surface of said key member apart from each other.