Paul Rumpf wrote in 080805 MMDigest:

> The silencer is a pneumatic that shuts off vacuum to the stack.
> It stops the stack playing but allows the motor to continue
> driving the roll forward.

On my brother's H. C. Bay the "silencer" button also operates the
governor bypass, allowing the motor to continue moving the roll
forward, but at higher speed, allowing one to bypass large sections
of roll fairly quickly.

Bob Loesch
Northern California, USA