MTS Hand-Operated Hydraulic Pump - Manual (Page 7)

Hand-Operated Hydraulic Pump 7
D. Apply sufficient pressure to the grips and check for leaks at all fittings.
Sufficient pressure will be determined by the gripping force
specifications of the grip.
E. After ensuring that all connections are leak free, open the pressure
release valve to release the pressure in the grips.
With the reservoir end of the pump pointed up, fill the reservoir with Quaker
Quintolubric hydraulic fluid, or equivalent. If the level is ever low, add more
hydraulic fluid.
Determine the Gripping Pressure
Improper grip pressure can damage the grips and cause possible personal
injury.
Insufficient grip pressure can result in specimen slippage or wedge
movement which can damage the grips.
Using a grip pressure that exceeds the pressure rating of the grip can result
in damage to the grips.
For hydraulic grips and fixtures, make sure that the hydraulic supply pressure is
limited to the maximum pressure defined by the grip or fixture identification (ID)
tag.
The amount of hydraulic pressure to be applied to the grips must be sufficient to
prevent backlash between the specimen ends and the specimen adapters, and also
between the mating threads of the specimen adapters and the grip extensions,
during all parts of the loading cycle.
To also ensure that the grips will not be loaded beyond their force rating,
however, determining hydraulic pressure must start with temperature
considerations, rather than the forces to be applied to the specimen.
Note If the gripped ends of the specimen become deformed, reduce the
hydraulic gripping pressure. Re-compute the amount of pressure
required to grip the specimen.
Determining the required hydraulic pressure is a two step process:
1. Determine that the maximum force (whether tensile or compressive) to be
applied to the specimen is within the grip rating, considering the
temperatures that the specimen will experience.
2. If anticipated forces are appropriate, use the “Required Pressure for the
Applied Force” graph to find the required gripping pressure.