Gear Pump Rear Cover with Integrated Relief Valve - Group 1 and Group 2

This is the rear cover off a Group 1 or Group 2 gear pump with a relief valve built into it. It replaces the plain cover on the back of the pump, so the pump protects its own circuit. No separate relief valve, no extra manifold, no extra plumbing - the pressure setting lives in the pump itself.

Fitters use these when there is nowhere sensible to mount an inline relief, on tight tipper and tail-lift installations, on 12 and 24 volt power packs, and on any circuit where a customer might dead-head the pump against a closed valve. Pick your frame and pressure band below.

Ways to buy this cover

• Off the shelf: six covers - Group 1 and Group 2, in three pressure bands each. Pick from the dropdown.
• Already own the pump? This cover bolts onto an existing pump of the same frame. You do not need a new pump.
• Buying pump and cover together? Order the pump from the Group 1 or Group 2 listing and add the cover here - we will assemble and pressure-set it before it ships if you tell us the setting you want.
• Group 3 pumps: the factory does not build an integrated relief cover for the Group 3 frame. Use an inline or cartridge relief valve instead, or send us the circuit and we will size one.

Pick your cover

What is in the box

• One rear cover with the relief cartridge fitted and the adjusting screw locked
• Cover O-ring and body seal
• Mounting screws to suit the frame

The pump body seal set is NOT included - if the pump has been in service, fit a fresh seal kit at the same time. There is a link below.

Specifications

How to choose

• Frame first. Measure the pump mounting flange - 32mm across the register is Group 1, 36mm is Group 2. Getting this wrong means the cover will not bolt on.
• Then the band, not the number. Pick the band your working pressure sits in the MIDDLE of, not at the top. A relief set at the very top of its range chatters and runs hot.
• Typical settings: tail lifts and tarps 120-160 bar, tipper hoists 180-210 bar, log splitters 200-250 bar, presses 250-320 bar.
• Not sure what the circuit needs? Call us with the ram bore, the load and the pump displacement and we will work the setting out with you.

Technicians Advice

The mistake we see most often with these covers is people setting the relief with no load in the circuit. You cannot - the valve never lifts, so the gauge only shows line loss and you end up screwing the adjuster all the way in. Set it against a real load: extend the ram to the end of its stroke, hold the lever over so the pump is deadheading through the relief, and read the gauge THEN. That is the only reading that means anything.

Second thing: this cover returns relief flow internally, back to the pump inlet, not to tank. That is what makes it neat, and it is also its limit. Oil that keeps cycling through the pump instead of going back to a tank picks up heat fast. If your operator sits on the lever with the ram bottomed out for a minute at a time, every minute, you will cook the pump - and the shaft seal goes first. On duty cycles like that, use a proper external relief plumbed to tank and leave the pump cover plain.

Third: torque the cover screws evenly and in a cross pattern, and do not exceed the pump maker figure. These are aluminium bodies. Over-torque one corner and you distort the gear housing, which puts a wear step in the gear faces and kills the pump inside a hundred hours. If you have the pump apart anyway, replace the shaft seal - it costs almost nothing next to the labour of dropping the pump twice.

Complete your setup

Fitting out a fleet or buying several? Call us and we will work out freight and lead time on the whole lot.

Shipping and Freight Information

We ship Australia-wide. Orders are dispatched from our supply network in Melbourne, Brisbane and Perth, so your parts leave from the warehouse closest to you on express freight.

Out of Stock Policy

It is our intention to hold stock on every listed item. If a size is temporarily unavailable you will be told straight away and offered a full refund or a short wait for incoming stock.

Need help choosing? Call 1300 146 737 or email sales@mhfgc.com.au - real technicians, real answers.