Dear Sirs

We got an 2 axis CNC lathe with Turret controlled by Hydro motor and positioned by encoder

Hydraulic manifold has a Creep valve and speed during creep can be controlled thro flow control on this Creep valve

When we command a station, turret rotates in rapid and just one station before the programmed tool stations , it gets slowed, after this most of the times, it does not get clamped

a) We tried by replacing creep valve from another similar machine

b) To avoid backlash due to worm wheel and worm shaft of turret assembly, we started commanding such that Turret always in only one direction

No effect

Can any one advice please what else to be checked, we feel nothing wrong with PLC logic and encoder which counts station . This machine is about 20 years old and i dont remember if worm wheel and worm shaft etc were replaced any time, but then we think even if there is any wear and backlash is more it should have got compensated in uni directional movoement

Warm Regards