This view shows the whole engine assembly. The air pressure needed to run the engine is supplied by
4 hand pumps. Using fewer hand pumps results in reduced engine speed due to the high demands placed
on the air supply by 4 pistons.
This engine has been clocked at 51 rpm and has considerable torque.
The air tank supplies 2 pneumatic switches at the front of the engine.
The 2 pneumatic switches are placed back-to-back. The outputs from the front switch are routed through
the 2-hole technic beam, while the 1-hole technic beam carries the input to the back switch. Each switch
controls 2 pistons on one side of the engine.
The main drive shaft (in the center with the yellow part on the axle) turns the 2 timing wheels on
each side, which in turn flip the pneumatic switches at the correct point in the cycle. The timing
of the 2 switches need to be 1/4 of a rotation out of synch with each other to insure that the engine
doesn't stall.
The 2 pistons on a side fire at the same time, one pushing while the other pulls, and are neccessarily
1/2 out of phase on the crankshaft with each other and 1/4 out of phase with the pistons on the other
side. The pistons on opposite sides are held at 90 degrees to each other through standard technic
contructions.
Starting the engine requires only pumping the hand pistons.
Click here to see an MPG of the V4 engine in action (635K)