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Heavy Duty Balanced Opposed Compressors

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FOR MODELS: JG AND JGA SECTION 5 - MAINTENANCE<br />

VVCP - Variable Volume Clearance Pocket Head End<br />

Unloader<br />

Removal<br />

Disconnect the VVCP packing vent. Remove the VVCP from the cylinder using similar procedures<br />

as when removing a cylinder head. The approximate weights of VVCP’s for handling<br />

purposes can be found in the Ariel Data Book.<br />

Disassembly<br />

Unsnap the thread protector bellows from the slot in the hand wheel. With the locking handle<br />

locked, remove locknut and hand wheel. A hammer or puller may be required to break hand<br />

wheel to stem tapered fit. Loosen locking handle and unscrew to remove handle. Remove<br />

socket head screws at inside of bolt flange and separate the halves of the VVCP. Unscrew<br />

the VVCP stem and piston assembly to remove.<br />

Maintenance<br />

!<br />

CAUTION<br />

TRAPPED GAS PRESSURE CAN PRESENT A PERSONAL<br />

SAFETY HAZARD WHEN SERVICING THE VVCP. WORK IN A<br />

WELL VENTILATED, NON SPARKING AREA. DO NOT<br />

BREATHE GAS OMMITTED FROM VVCP WHEN VENTING<br />

TRAPPED GAS.<br />

To replace or clean the VVCP packing, remove the bolts and flange that hold the packing in<br />

place and remove the packing. Replace the VVCP packing when excessive leakage is noted<br />

at the vent. Remove the VVCP piston ring; replace as necessary.<br />

Clean all parts to remove all debris, rust, etc. The stem and piston are permanently pinned,<br />

do not attempt to disassemble.<br />

Reassemble the VVCP in reverse order, using a new O-ring at the bolt flange. While the<br />

torque used for the socket head bolting is not critical, these bolts must be sufficiently tight to<br />

prevent loosening during service. Be sure that thread protector bellows are properly aligned<br />

when installing hand wheel. Lubricate stem with 3-4 pumps of all-purpose petroleum grease<br />

with a hand pump grease gun at the grease fitting.<br />

To re-install the VVCP on the cylinder, use a new head gasket. Lubricate threads and bolting<br />

seating surfaces with petroleum type lubricant and install bolting. Tighten each cap<br />

11/01 PAGE 5 - 35

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