Ku nst sto ffschwei ß tec hni k
Maintenance and repair Chapter 7
02.11.11 Working instructions WIDOS 4900 Page 29 of 46
7.6. Venting the hydraulic cylinders
Venting the hydraulic cylinder is not required, if
• the hoses have been disconnected from the connection at the control unit because the
remaining oil in the hose is being kept by valves and for this reason no air can enter.
Venting of the hydraulic cylinder is necessary, if
• there has been too little oil in the tank and air has been attracted.
• there were leaky parts in the hoses or connections.
• the hoses were unscrewed from the basic machine.
• Eliminate the cause of the air entrance.
• Open the machine completely.
• First loosen the lower venting screw (A1) for closing (lefthand side).
• Connect the transparent venting hose and insert into the collecting vessel.
• Close until there is no air in the venting hose, then screw on the venting screw.
• Repeat the same process at the upper venting screw (A2) for closing (left).
• Close the machine completely.
• First loosen lower venting screw (Z1) for opening (righthand side).
• Connect the transparent venting hose and insert into the collecting vessel.
• Open until there is no air in the venting hose, then screw on the venting screw.
• Repeat the same process at the upper venting screw (Z2) for opening (right).
The lower venting screws have always to be vented in the first position because
there is a direct link between the upper and the lower cylinder.
• If there is still air in the lower cylinder this will ascent in the upper cylinder
under pressure.
Z2
A2
A1
Z1
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