MTS Series 311 Load Frame - Manual (Page 59)

Adjusting the Hydraulic Locks
Series 311 Load Frame Maintenance 59
Adjusting the Hydraulic Locks
Hydraulic locks will need adjustment if the crosshead does not move smoothly
after bleeding the lift cylinders. Adjustment might also be needed if the
crosshead slips under full load. If adjusting the hydraulic locks does not fix these
problems, contact MTS Systems Corporation.
1. Turn on electrical power at the controller. Do not turn on hydraulic pressure
yet.
2. If the crosshead is already at a comfortable working level with no specimen
installed, proceed to the next step.
If not, position the crosshead for a comfortable working level. Proceed as
follows:
A. Turn on high hydraulic pressure.
B. If there is a specimen in the load frame, remove it.
C. Unclamp the crosshead.
D. Move the crosshead to a comfortable working height.
E. Clamp the crosshead.
F. Turn off hydraulic pressure.
The crosshead can slowly drift down the columns if the locks are turned off
and the hydraulic pressure is turned off.
The crosshead can damage any test fixtures, grips, and specimen in its
path.
Unlock the crosshead only to reposition it. Always lock the crosshead after you
have repositioned it, and never leave the crosshead unlocked.
3. Install the shipping collars on diagonally opposite columns directly above
and below the crosshead. See “Shipping Collar Torque Specifications” on
page 35.
4. Use the Crosshead Lift/Lock Controls to the unclamp the crosshead to
remove pressure from the hydraulic locks. Wait two minutes for the pressure
in the locks to drop to zero before going on to the next step.
5. Use a spanner wrench to tighten the clamping piston onto the tie rod until all
slack is removed and the clamping piston bottoms into the cylinder.
6. Loosen the clamping piston 1/8 turn.
7. Repeat Step 5 and Step 6 for the remaining hydraulic locks.
8. Turn on electrical power at the test controller if you have not already done
so and reset any active interlocks at the test controller.
CAUTION