MTS Landmark Tabletop - Manual (Page 98)

b) If the pressure level corresponds to the level recorded on the accumulator label, turn the locknut
clockwise to close the valve and continue this procedure.
3. Open the bleed valve on the accumulator charging kit and remove the chuck valve from the accumulator.
Replace the valve stem cap and protective cover on the accumulator.
Change the Precharge Pressure
Often the precharge of an accumulator mounted on a hydraulic supply line is increased to enhance system
performance and reduce the transient HPS flow demands. Accumulators may be precharged to 10 MPa (1500
psi) or more, although amounts above 14 MPa (2200 psi) will have less and less performance effect in most
situations. Be sure that you read the following warning before you charge your accumulator.
Warning:
Accumulators have specific pressure ratings.
If the precharge pressure is too high, the accumulator can bottom out causing the release of
metal particles into the hydraulic fluid. Charging accumulators above their rated level can damage
system equipment.
Do not charge accumulators to pressures above their rated level. Charge accumulators below
their rated fatigue pressure of 21 MPa (3000 psi) for the Model 111.11B and 22 MPa (3200 psi)
for the Model 111.12C. Use a suitable regulator and gage set to an accumulator’s charges.
Decrease Pressure
To decrease the precharge pressure:
1. Slowly open the bleed valve on the accumulator charging kit until gas begins to escape. When the pressure
reading on the appropriate pressure gage drops to the level required, close the bleed valve.
2. Close the locknut (or close the chuck valve if you have a core-type valve). Open the bleed valve on the
accumulator charging kit and remove the chuck valve from the accumulator.
3. Install the valve stem cap and protective cover.
Increase Pressure
To increase the precharge pressure:
1. Close the locknut on the accumulator (or close the chuck valve for a core-type valve).
2. Open the bleed valve two turns.
98 MTS Landmark™ Tabletop Load Units Product Information
Maintenance