How To Check Your Valves

How to check your rotary valves

Here are some easy ways to check your valves to see if they may need servicing.  If you are unsure or have questions, please contact us!


Checking for Valve Leaks

There are a few different ways of checking for leaks in your valves. Many repair shops have air pumps with  pressure gauges that allow them to check exactly how much pressure the valve holds. It also allows them to check for leaks elsewhere in the instrument. The easiest way for  players to check their own valves is to simple pull the slide. Here is how to do this:

1) Without pressing the key, pull the slide half way out.
2) Wait one or two seconds.
3) Press the key.

There should be a pop sound. The louder the pop, the tighter the valve. If there is no pop, you have a leak. In the occasional tuba or euphonium, this method will not work because the valves are designed to allow for venting, but 99% of the time, it will.

Checking for End-play (End-Play: Valves move back and forth in the casing, which can limit the life of the valve)

1) Hold the stop-arm between your thumb and pointer finger.
2) Move the valve up and down, toward and away from the cap.  Listen for clanking or knocking.

If there is movement then there is end-play.

Common Causes of end-play:

-The bearing plate has been knocked loose over time during normal use,
-The  bearing surface wears down from normal use or not enough lubricating,                      -The bearing plate fits too loosely in the casing

In almost all cases, end-play can be removed with some subtle adjustments by a professional.

Checking for Side Play (Side-Play: Valves moving side to side inside the casing, which can reduce the life of the valve)

1) Hold the stop arm as in the end-play check.
2) Pull the stop arm down (away from the cap).
3) Move the valve side to side.

If there is movement then the valve has side-play.

Common causes of side-play:

- Wear of the stem in the port

-Side-play is usually indicative of greater problems with the valve. In some cases this can be fixed through an adjustment to the valve stem port. In more extreme cases it may be necessary to rebuild the valve entirely.