How to tilt a truck cab: Mercedes-Benz, Volvo FH, DAF XG

A truck cab is tilted with a hydraulic pump in four moves: secure the truck, set the selector valve on the pump to tilt, pump until the cab passes over centre, then let it travel all the way forward under its own weight. To bring it back, set the valve to lower/drive and pump until the cab locks. What differs between makes is where the pump is and whether it is worked by hand or by an electric motor.

What has to be done before the cab is tilted?

Switch the engine off, apply the parking brake and select neutral. Diesel Technic’s instruction sheet for its hydraulic cab tilt system (DB6010) requires all three for tilting and lowering alike, and asks for “adequate clearance in front and above the cab”. DAF’s driver training video for the XG adds level ground, and the reason for the clearance: the cab “will travel forward in an arc”.

Inside the cab, Volvo’s online Driver Guide wants no loose objects, doors “either fully open or firmly shut” and the fridge emptied and switched off. The Mercedes-Benz driver video warns that loose items can “fall through the windscreen”.

The front panel comes last. Mercedes-Benz: “It is imperative that the maintenance flap is raised into the open position first.” Volvo says the same of the front hatch on the FH; left shut, it is damaged as the cab comes over. On the DAF XG the grille panel is opened fully.

Where are the pump and the selector valve, and how are they set?

The pump carries a two-position selector valve. On the hand pump in DB6010, fully clockwise is UP and fully anticlockwise is DOWN/DRIVE. Volvo’s FH works the same way round: its valve is turned with a socket wrench “clockwise to the stop position” to tilt. Where the pump sits differs from truck to truck.

Animated diagram

Lift Lower Stop pumping

Pump stopped: the check valve closes, the oil under the piston is trapped, and the cab stays where it is.

The Mercedes-Benz, DAF and Scania rows come from documents for the Australian market, which is right-hand drive; “driver’s side” and “co-driver’s side” are their own words, and these documents do not say which side the pump is on in a left-hand-drive truck. The Volvo row is from the Driver Guide (FH Aero, FH16). Each row describes only the truck in its document; a dash means it does not say.

How do you pump the cab up, and when do you stop?

With the selector at tilt, work the pump. DB6010 describes what happens next:

“When the cab has reached and passed its top dead centre (TDC), the cab will move forward without any further pumping through its own weight.”

Diesel Technic, Assembly Instruction DB6010, Version 1, 9 September 2024

The speed of that movement, the sheet adds, is set by a restriction orifice that throttles the oil leaving the top of the cylinder. Volvo puts it in the driver’s terms: pump until the cab “passes its top position and continues tipping of its own weight”. No work starts under the cab until it has gone all the way forward.

What is different with an electric pump?

In the Mercedes-Benz video and in Volvo’s handbook, an electric pump takes over the pumping, not the valve. The order is the same in both: a switch in the cab enables the pump, the selector valve is still set by hand at the pump, and a button is held down until the cab is fully tilted. On the Mercedes-Benz the dash switch lights up red when the system is active. On the Volvo the truck must be in vehicle mode Accessory or Pre-running, with the key remote left in the cab.

Volvo adds two notes. A cab with the electric pump “can also be tilted mechanically if necessary”, with the pump lever. And if it is tilted electrically more than twice in a row, overheating protection may cut in: the motor is left to cool for 15 minutes, and if the pump still does nothing, the fuse in the cab is checked.

Scania Australia’s new-generation brochure places the electric pump “on the driver’s side behind the front grille panel”, switched from the instrument panel; a mechanical version is also offered.

How do you lower the cab, and how do you know it has locked?

Check the path first; DAF’s video has the driver look for obstructions and stand in a safe place. Set the selector to lower/drive and pump. In the system DB6010 describes, the cab comes down only while you keep pumping, and near the end of its travel it drops into its locked drive position. DAF calls this “a slight drop”, which engages the cab locks automatically.

The pump and the dashboard tell you it has locked. Mercedes-Benz asks for several more strokes after the locks engage, “until there is a noticeable resistance felt”, and for the cab tilt lamp in the instrument cluster to go out before the engine is started: “When the indicator goes out, the cabin is locked.” Volvo has the driver check for a cab-tilt-unlocked notification at the next start.

Leave the selector in lower/drive. DB6010 requires it to stay there whenever the truck is driven.

What if the cab will not tilt, or stops part-way?

Volvo’s handbook gives two possible reasons for a cab that cannot be tilted: it is too heavily loaded, or there is air in the system. For the rest:

• Pumping builds no pressure. Volvo notes that the system may need bleeding; see bleeding a cab tilt pump.
• The cab does not move, stops part-way or will not come back down. Latches, selector, oil level and the pump pressure test are worked through in cab won’t tilt, won’t lower or creeps down.
• A wet hose or a falling oil level. Finding and changing the right hose is in the cab tilt hose guide.

The exact position of the pump and the name of the switch are in the truck’s own handbook. The order of work does not change.