Posted by How on June 02, 2002 at 18:18:56:
In Reply to: Compensating Valves posted by Patrick on June 02, 2002 at 16:46:42:
Pistons #1, #2, and #3 each have an extra cross-tube (three cross-tubes each, instead of two).
When the 4th valve is depressed, the #4 loop is send back through the pistons and an extra loop of tubing (one loop located on each of the 1-2-3 pistons) is added when any of the valves 1-2-3 are depressed. These loops are usually found on the backs of the 1-2-3 valve casings. These added loops are just about the correct lengths to make the combination of 1,2, or 3 in conjunction with the 4th valve be in tune, instead of very sharp.