Rotary valves if properly looked after are very reliable and give years of trouble free service.
This blog gives guidelines to maintaining rotary valves in good condition. Very little maintenance is required, but some is important.
Rotary valves will rarely actually stick in use like pistons, but if not maintained will start getting slow and possibly noisy.
Two sorts of oil are required for rotary valves. A thicker oil for external use and thin oil for inside the tubing. For the thicker oil either get specifically sold rotor valve oil (such as sold for French horns), or sewing machine oil. For inside the tubes normal piston valve oil will be suitable.
We would recommend oiling about once per month to keep the rotary valves in good condition. Unscrew the back-plate of each rotor and put one drop of thicker oil on the central bearing. Screw the plate back on not too tight. Then put drop on the front axle of each rotor and on each moving joint in the linkages. Don’t put too much – only one small drop.
While oiling check that all screws are fully in and none are working loose through vibrations.
Then take out the mouthpiece and tip the tuba to put three drops of oil down the leadpipe, replacing the mouthpiece and blow while waggling the valves. This is to coat the inside of the valves with some oil. This is not essential and the valves if in good condition should not rub internally, but the oil reduces lime deposit which may otherwise in the long term slow the valves.
About once every 6 months according to use we would suggest flushing the inside of the valves with hand hot soapy water (like you would wash the dishes) to remove and food particles which may have blown into the valves. You can do this by pulling out the main tuning slide and turning the tuba to pour about half litre water in. Waggle the valves while the water runs through and turn tuba to let the water come out of leadpipe. A pipe cleaner can be used on leadpipe at the same time to loosen dirt which will then come out at the mouthpiece rather than going into the valves. Pull all the tuning slides out and turn tuba to completely empty water. This is best done in the bath.
Then leave all the slides out overnight to let the inside dry before returning and re-oiling tuba. This is also a good time to replace slide grease on the tuning slides.
Leaving for Holiday
If tuba is not to be used for prolonged period (over one week), for example while on holiday, always oil the inside of the valves before leaving. If valves are stuck on return then turn the actual rotor spindle direct by hand to free and do not use the valve buttons so the linkage is not bend
Hopefully with that simple maintenance your rotors will be trouble free for years to come. If you do experience any problems then always first clean as dirt is usually the problem.
However, if that does not work then best to take tuba to professional brass repairer to check and don’t try to dismantle the valves yourself as rotary valve repair is not really a job for the inexperienced. © Jonathan Hodgetts