Forklift attachment hydraulic requirements

A forklift uses its base hydraulic functions for lift and tilt. Anything an attachment does — shifting, positioning, clamping, rotating, tipping — needs an additional double-acting auxiliary service, each with its own valve section and its own control in the cab.

Trucks are commonly delivered with one or two spare auxiliaries, sometimes none. Fleet trucks bought for plain fork work are often the ones with none, which is exactly the situation an attachment upgrade runs into.

• Side shifter — one double-acting service.
• Fork positioner — one service; two if side shift is integrated.
• Clamps (bale, carton, block, drum) — one service for clamping.
• Rotating clamp or rotator — two services: rotation plus clamping or shifting.
• Bin tipper, hinged carriage, pusher — one service for the tipping or push function.
• Mechanical families (extensions, jibs, drum handlers, platforms) — none.

A solenoid selector valve lets two functions share one auxiliary service, switched from the cab. It is a well-proven answer and often the cheapest one; the trade-off is that the two functions cannot be operated simultaneously, so the operator sequences them.

The alternative is adding a valve section and plumbing a genuine extra service. That is a bigger job on the truck and worth doing where both functions are used constantly, or where the truck will carry attachments for years.

Service count is the first question but not the only one. Rotating and high-cycle attachments care about available flow — too little and rotation is slow, too much and relief valves get hot. Pressure has to match the attachment’s rating, and hose routing up the mast needs a reeler or an internal hose arrangement that suits the mast type.

None of that is exotic, but all of it is easier to settle before the attachment arrives than after. Sending the truck’s make, model and mast type with the enquiry is usually enough for us to flag anything that needs attention.