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2.4
Installation of Accessories
Spherically-seated breaking heads and other top-mounted platens are held in place by a locking stem secured
by a hex (Allen) head set screw. For AC-325 and AC-450 series machines, the set screw is installed in the front
of the upper crosshead.
For the AC-250 series, the set screw is partially obscured when the loading piston is in the home position. To
access the set screw, advance the piston about 1in and place the hydraulic control in the hold position.
Lift the accessory into position, inserting the holding stem firmly into the hole centered inside the frame. Then,
tighten the set screw against the holding stem, locking the accessory in place. There should not be any force
on the holding stem or set screw during testing. The force should be between the frame and blue seat of the
testing accessory.
Note regarding Unbonded Capping: The sudden release of energy (when the specimen breaks) associated
with rubber pad caps can greatly reduce the life of hydraulic and mechanical components. Pad caps are not
recommended for prolonged testing beyond 60% of the machine's maximum capacity.
3.0 HYDRAULIC SYSTEM SETUP
Keeping the unit clean and the fluid free of dirt will increase the life of the pump, valve(s), and other hydraulic
components. The fluid reservoir is filled prior to shipment with Dexron III Automatic Transmission Fluid (ATF).
Fluid capacity is approximately 2 gallons, and fluid level should be approximately 2in from the top of the reservoir.
See Section 8.0 if addtional fluid needs to be added.
Testing accessories should be cleaned as needed. Spherical discs and seats should be disassembled, cleaned,
and lubricated periodically with a light lubricant such as Dexron III ATF or spray lubricants. Do not use heavy
lubricants such as grease, as dust and debris will collect in it and prevent the unit from rotating properly.
The reservoir should be drained and replenished with clean fluid at least once a year. The frequency of the fluid
change will depend greatly on the general working conditions, hours of use, and the overall cleanliness and
care given to the system.
3.1 Bleeding Air from the System
Upon initial startup, air can accumulate within the hydraulic system. The trapped air can cause the system to
advance slowly or to surge and make the motor become noisy. To remove the trapped air:
• With fluid in the unit and the machine ready to operate under zero load, advance the piston about 2in of
travel and then retract to the starting position. This should be repeated several times to work the air out of
the system. If this does not remove all trapped air, continue to the next step.
• With fluid in the unit and the machine ready to operate under zero load, loosen a couple of turns, but do not
remove, a hose fitting that is situated higher than the rest of the hose fittings in the system. Run the pump
until a steady flow of fluid, free of air bubbles, is observed. Retighten the fitting.
3.2 Checking and Maintaining the Fluid Level
NOTE: The following operations should be performed with the power off and the piston retracted to
effectively determine fluid level.
• After locating the pump and motor assembly, find the plug on the top of the reservoir cover plate.
• Check the fluid level in the reservoir by removing the fill plug and inserting the dipstick in the reservoir. The
system is full when the fluid level measures 2in below the top of the tank when fully retracted. Overfilling may
cause performance issues, leaking, and/or damage to the pump, motor, or valve(s).
• When it is necessary to add fluid to the reservoir, remove the cap and fill it to the proper level with Dexron III
or VI ATF. The reservoir capacity is approximately 2 gallons.
Automatic Concrete Compression Machine Manual
7
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