Air brakes for trucks

The present invention provides an improvement in an actuator system for use with a brake system of the type including a brake and a source of compressed air which is connected to an air chamber including a push rod for moving a transverse brake actuator bar between a brake applied position and a brake released position. The push rod operates the transverse brake actuator bar. The actuator system includes an asymmetric operator member which is relatively-rotatably-attached to a non-rotatable wheel support, and which is concentrically-disposed around an axle of a wheel. The asymmetric operator member includes an ear which is attached to the transverse brake actuator bar. A brake arm assembly includes a pair of diametrically-opposed arcuate brake arms, each brake arm including an inner arcuate channel member, one end of the arcuate channel member terminating in a hollow cylindrical bushing, the other end of the channel member terminating in a pair of transversely-spaced-apart ears having aligned apertures therethrough. An inner anchor plate and an outer anchor plate sandwich the asymmetric operator member therebetween and also are relatively-rotatably-attached to the non-rotatable wheel support which is concentrically-disposed around the axle of the wheel. The anchor plates are non-rotatably-secured to the asymmetric operator member. A first bifurcated link is rotatably-attached between the ears of a first channel member and the anchor plates, and a second bifurcated link is rotatably-attached between the ears of a second channel member and the anchor plates. A first hollow cylindrical bushing is rotatably-attached to the anchor plates opposite to the attachment of the second bifurcated link, and a second hollow cylindrical bushing is rotatably-attached to the anchor plates opposite to the attachment of the first bifurcated link. On activating the air pot, the push rod moves the transverse actuator bar to rotate the asymmetric operator member in a counter-clockwise direction, to urge the arcuate brake arm to move in a braking action radially-outwardly from an inactive position towards, and frictionally-engaging, radially-inwardly-facing brake pads, and on venting compressed air from the air pot, the push rod moves the transverse actuator bar to rotate the asymmetric operator member in a clockwise direction, to urge the arcuate brake arms to move in a brake releasing action radially-inwardly to inactive positions away from, and out of frictional engagement wit