Sometimes I have seen it referred to as "rack dampener" so you might try that spelling too.
The classic rack dampener issue is a shaking idle when hot (especially just after an interstate run) but not much of a shake when cold.
Other things that can have an impact are the motor mounts and motor shock absorbers. You can also have a cylinder with low compression that is causing the shake.
Tell us more about the circumstances of the "sometimes" and it might be possible to do an "internet diagnosis".