Figure 4-40.Antidieseling solenoid operation.
Without the throttle return dashpot, the engine
could stall when the engine quickly returned to idle.
The drag of the automatic transmission could kill the
The throttle return dashpot works something like a
shock absorber. It uses a spring-loaded diaphragm
mounted in a sealed housing. A small hole is drilledinto
the diaphragm housing to prevent rapid movement of
the dashpot plunger and diaphragm. Air must bleed out
of the hole slowly.
Figure 4-41.Throttle return dashpot
When the vehicle is traveling down the road
(throttle plates open), the spring pushes the dashpot
plunger forward. When the engine returns to idle, the
throttle lever strikes the extended dashpot plunger, and
air leaks out of the throttle return dashpot, returning the
engine slowly to curb idle. This action gives the
automatic transmission enough time to disconnect
(torque converter releases) from the engine without the