Tubular push rod means for servomotor

Claim 1

In a servomotor having a wall means separating a front chamber from a rear chamber, valve control means for regulating the communication of a fluid, whose pressure varies over a range from a vacuum to air at atmospheric pressure to air above atmospheric pressure, to said rear chamber to create an operational pressure differential across said wall means with a fluid at a vacuum pressure in the front chamber in response to an input force reacting to an operational output condition, said valve control means comprising: hub means connected to said wall means having a housing with a bore therein, said housing having a first passage connecting said bore with the rear chamber and a second passage connecting said bore with the front chamber, said hub means having a vacuum seat located between said first and second passages; first poppet means located in said bore having a face on a first End with an opening therethrough and a lip on a second and secured to the housing surrounding said bore; sensing means connected to said rear chamber for comparing the pressure of the fluid therein with the pressure of air at atmospheric pressure to create an actuation output for directing said air above atmospheric pressure to said servomotor; tubular push rod means having one end connected to a head member and another end connected to an actuator, said tubular push rod means having a first opening adjacent the actuator connection, said first opening being connected by a conduit to said air above atmospheric pressure at the sensing means and a second opening adjacent said head; said poppet means having a first rib secured to said tubular push rod means between said first and second openings and a second inwardly projecting rib located between said second opening and said head member, said air under pressure being communicated through said tubular push rod means and out said second opening into said second poppet means to urge said second rib against said head member and contain said air under pressure in said tubular push rod means; and plunger means connected to said head member and located in said axial bore, said plunger means being moved by an input force from an operator for sequentially regulating the communication of a vacuum available in said second passage through the first passage into the rear chamber in a first position, the communication of air at atmospheric pressure through the bore into the rear chamber through the first passage upon termination of the vacuum communication through the second passage by engagement of the first poppet means with said vacuum seat in a second position, and the communication of air above atmospheric pressure contained in the tubular push rod means into the rear chamber upon engagement of the second rib of the second poppet means with the first poppet means in a third position to develop said operational output.