MTS Series 111 Accumulator - Manual (Page 32)

maintained within the limits, remove the fluid and charge the accumulator. If the levels are again exceeded
at the first check interval, replace the piston seals after the initial fluid has been changed.
• If the precharge pressure level decreases at each check interval, this indicates gas leakage to the fluid
side. When the precharge pressure level cannot be maintained within the limits stated in the previous
guidelines, replace the accumulator piston seals.
• During normal operation, the accumulator piston should be near the center of the accumulator cylinder.
To check the approximate piston location, note the warm-to-hot transition point on the accumulator cylinder
wall during operation. If the piston is near the charging stem end, the accumulator may need charging. If
the piston is at the other end, the accumulator may have an excess charge, or more likely an excessive
amount of hydraulic fluid has collected in the gas chamber.
6.2.0 Check the Accumulator Precharge
The following equipment is required for any Series 111 Accumulator: Accumulator charging kit (MTS part
number 376986-01).
1.
Warning:
Accumulators are pressurized devices.
Pressurized accumulators and their parts can become lethal projectiles if disassembled
and can cause death to persons and/or damage to equipment.
Do not remove an accumulator that is pressurized. Completely remove hydraulic pressure
and discharge the accumulator before any parts, except the protective cover and valve stem
cap, are removed.
Ensure that system hydraulic pressure has been reduced to zero before proceeding. To do this, turn off
the hydraulic power unit and exercise the actuator until it stops moving.
2. Close the bleed valve on the accumulator charging kit. Remove the protective cover and valve stem cap
from the accumulator (see “Accumulator Components” and the figure below).
3. Check the precharge depending on the kind of accumulator on your system.
a) For an MTS Series 111 Accumulator, see "Check the Series 111 Accumulator Precharge".
b) For a non-MTS accumulator, see "Check a Non-MTS Accumulator Precharge".
32 Series 111 Accumulator Product Information
6.0 Maintenance