DGUV Information 209-071e - Safe maintenance of hydraulic systems (DGUV Informat...

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Abschnitt 6.2, 6.2 Working on industrial trucks
Abschnitt 6.2
Safe maintenance of hydraulic systems (DGUV Information 209-071)
Titel: Safe maintenance of hydraulic systems (DGUV Information 209-071)
Normgeber: Bund
Amtliche Abkürzung: DGUV Information 209-071
Gliederungs-Nr.: [keine Angabe]
Normtyp: Satzung

Abschnitt 6.2 – 6.2 Working on industrial trucks

6.2.1 General

Depending on the type and extent of repair works on mobile hydraulic systems of industrial trucks, this work is conducted by internal operating departments, mobile maintenance services, or at service locations of the manufacturers or dealers.

In industrial trucks mobile hydraulic systems are used for

  • the traction drive,

  • the lifting frame with tilting device,

  • the adjustment device for fork-lift forks or the pivoting device,

  • the power-assisted steering system.

If maintenance work on industrial trucks poses hazards caused by possibly bumping against the fork-lift forks, e. g. in the area of traffic paths, the forks have to be removed before starting any works. This also applies to the lifting of the industrial truck using a hoisting platform.


Fig. 35
Lifting forks removed for working on the hydraulic system of a fork-lift truck

6.2.2 Traction drive

If replacing the traction drive hydraulic motor requires the lifting frame to be lifted, the frame has to be secured against lowering in accordance with the manufacturer’s specification.

6.2.3 Lifting cylinder

The safe condition of the lifting frame is essential for the operational safety of the industrial truck. Repairs should only be conducted by especially trained personnel, e. g. with the manufacturer, or by the customer service. The manufacturer’s specifications have to be observed during all works on the lifting frame.

Before starting any works on lifting cylinders, the lifting frame has to be lowered, supported, driven into a frame, or blocked mechanically. Working on telescopable lifting frames, e. g. in duplex or triplex design, should be left to the customer service.

When installing a new lifting cylinder, it has to be observed that the hydraulic hose assemblies are inserted properly into the designed guiding/deflection pulleys.

On older industrial trucks with hose rollers at the side of the lifting frame it has to be observed that the hose assembly is subject to spring force on the roller side. When loosening the connection, the hose assembly has to be secured against whipping, e. g. by means of a second person. In doing so, the hazard of being pulled in or pinched has to be observed at the hose roller.

6.2.4 Tilting cylinder

Before starting to work on the tilting cylinders, the lifting frame has to be secured against moving due to its dead load in accordance with the manufacturer’s specifications. This is done for example by lashing the lifting gear in the rearmost position using the designed attachment points or on the driver protection roof (see figure 36).

The tilting cylinders have to be filled with hydraulic fluid before being installed (see section 4.4).


Fig. 36
Lashed lifting frame when working on tilting cylinders

6.2.5 Power-assisted steering

As the installation space of the steering axis unit below the industrial trucks is very narrow, it seems to be advisable to disassemble the complete steering axis unit when working on the steering hydraulic system. The disassembly has to be carried out in accordance with the manufacturer’s instructions.

If there are accumulators in the hydraulic circuit of the steering system, they have to be depressurized before starting any works.