Failure and troubleshooting of hydraulic system

FAILURE AND TROUBLESHOOTING OF HYDRAULIC SYSTEM

INSTALLATION OF A HYDRAULIC SYSTEM

• Any hydraulic system requires careful planning, proper installation and start-up sothat to operate the system economically, safely, and trouble-free.

• With mobile installations, the mounting and the pipework connection of the hydraulic components are usually carried out by the manufacturer.

• In case with stationary installations, pre-assembled units or sub-assemblies are delivered. Sometimes, the initial installation is then carried out by the machine manufacturer, and often, it can only take place at the final set up location.

• The following points are to be observed during the installation of a hydraulic system:

(i) Visual inspection for transport damage and contamination is to be carried out initially.

(ii) Setting up and fitting of aggregates and sub-assemblies are checked for proper connection of the hydraulic system to the machine. With piping and hose installations, the longer lines are to be flushed through.

(iii) Electrical installation for the drive and for the controls is only to be carried out after the connection specifications have been checked (wattage, etc.). If necessary, connect the coolant supply. Check the correct direction of rotation of the pumps before switching on.

(iv) Filling the reservoir with the specified (or equivalent) hydraulic fluid.

• In order to guarantee the trouble-free operation of the installation, it is important that the appropriate hydraulic fluid with correct viscosity is used. 

• Area close to the hydraulic installation is to be kept clean. Before opening, always the filler opening plug or screw cap has to cleaned on the storage vessel or transportation vessel from which the hydraulic fluid is to be taken.

• The oil reservoir is to be checked for dirt and, if necessary, also clean before opening and filling. One should also check that the hydraulic fluid has not been contaminated with water. When filling or topping off, the filter strainer should not be removed either from the filler opening spout or the filter element. Wherever possible, always a filling device is to be used which incorporates a special filter.

(v) Filling the pump housing (in the case of piston-type pumps).

(vi) Opening the valves on the suction lines.

(vii) Setting the valves. With variable capacity pumps, the pressure control valves, flow control valves, and pressure compensators are to be adjusted to as low a setting as possible. Also the directional control valves are to be set to their at-rest position.

(viii) Charging the accumulators to their specified pre-charge pressures.

(ix) Checking the correct direction of pump rotation by briefly pressing the electric motor start button so that the motor only turns a few revolutions.

(x) Bleeding the system at the load lines, as far as possible at the highest points. It is carried out by operating the directional control valves and allowing the loads to move in and out a number of times. First the load alone is increased slowly, then the setting of the pressure control valves and/or pressure compensators are increased. Bleeding has been completed correctly when no more foam appears in the reservoir, when all load movements are smooth and free from Jerks, and when no abnormal noises are present.

(xi) Checking hydraulic fluid level. If necessary, the hydraulic fluid can be topped off after bleeding has been completed.

(xii) Final valve setting and placing the machine in operation. This is to take place in accordance to the manufacturer's instructions. Usually adjustments are made at the pressure control valves, pressure switches, flow control valves, pump controllers, switch settings, etc.

(xiii) Monitoring the operating temperature. After it has been running at full load for a number of hours, the final operating temperature should not have risen above 70°C. The cooling requirements must be checked based on the increase in operating temperature.

(xiv) Repairing leaks. It is usually sufficient to tighten suspect fittings after the installation has been running for a number of hours.

(xv) Cleaning the filters (or replacing filter elements). It should be noted that the largest amount of contaminant is trapped within the first few hours of operation.