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

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Abschnitt 6.3, 6.3 Working on hydraulically driven vehicle a...
Abschnitt 6.3
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 6.3 – 6.3 Working on hydraulically driven vehicle attachments and superstructures and vehicle cranes

6.3.1 General

As vehicle attachments or superstructures are often characterized by high weights, e. g. derrick booms, cranes, swivel towers, and due to the influence of gusts of winds during maintenance works in open territory, these attachments and superstructures pose a huge hazard when lifted.

Furthermore, it has to be observed that trapped pressures could exist due to hydraulically elevated loads. Basically, elevated loads have to be lowered or supported in a safe manner (see figures 37 and 38). The system must be depressurized and the depressurized condition must be checked. Further notes on maintenance work on vehicles can also be found in section 5.9.3 of the DGUV Regel 109-009 "Fahrzeuginstandhaltung" (Vehicle maintenance).

Attachments, swivel towers, derrick booms, or the like that are not affected by the repair works, should be moved out of the work area before starting any works.


Fig. 37
Safety support on an hydraulically elevated vehicle superstructure


Fig. 38
Boom of a concrete pump lowered to the ground

6.3.2 Vehicle main pumps

Vehicle main pumps are characterized by high masses and can be removed more easily using lifting gear.

Pumps installed below the vehicle can be positioned on the workshop floor, hand forklift truck or cavity cover below the vehicle with the help of lifting gear (see figure 39). The cavity cover has to have the corresponding load-carrying capacity.


Fig. 39
Vehicle main pump on a load lifting device

6.3.3 Protecting accumulator and hose assemblies

If there is the danger of mechanical damage to installed accumulators or hydraulic hose assemblies during the maintenance work, they have to be removed or screened for the time of the maintenance work.

6.3.4 Replacing cylinders

When disassembling hydraulic cylinders, there must be no external forces on the support points (piston rod and cylinder bottom side). Thus, the booms have to be supported completely or positioned on the floor.

Hydraulic cylinders may be pressurized - even if the load has been lowered. This pressure has to be reduced via the corresponding check valves (piloted check valve) on bottom and rod side or by loosening the fittings carefully before disassembly.

It is reasonable to fill the new cylinders to be installed with hydraulic fluid beforehand and to vent them (see section 4.4).

6.3.5 Checking the hose assemblies

When conducting annual vehicle checks (according to § 57 of the DGUV Regulation 70 and 71 "Fahrzeuge" [Vehicles]) or when checking the attachments or superstructures, the hydraulic hose assemblies have to be checked as well (see section 4.3.5).