Deceleration Valve: Description and Operation

Fig. 13 Deceleration vacuum valve:

The main component of this system is the deceleration vacuum valve, Fig. 13. This consists of an aneroid capsule (15a), which is activated by intake manifold vacuum (port 1). This capsule is connected to a barometric compensating diaphragm (15b) with manifold vacuum on one side (port 1) and atmospheric pressure (PA) on the other side. The rod (15c) is activated by the expansion of the aneroid capsule (15a) and the movement of the diaphragm (15b). During acceleration, ports 2 and 3 are connected. During deceleration, ports 1 and 2 are connected.