WARNING: Before working on a double acting telescopic cylinder mounted on a truck or trailer unit, use supports or holding devices that will absolutely prevent the body from accidentally lowering. Place control valve in the “LOWER” position to assure that all pressure has been relieved from the cylinder.
Double Acting Telescopic Cylinder Recommendations
- A double acting telescopic cylinder should be fully retracted when not in use.
- A double acting telescopic cylinder should not be extended until it has been fully retracted.
- A partially extended cylinder with pressure relieved may drift out of position. This can happen if a cylinder experiences vibration, such as an ejector or push out cylinder does in a refuse body. If this happens and the cylinder is then extended, the out of position plunger or sleeves will rapidly reposition themselves and possibly cause high pressure oil to be trapped on the retract side of the cylinder. This could cause a stage / sleeve to bulge and or the packing and bearings to be blown out from under a head nut.
- Do not operate a packer / ejector cylinder with a misaligned blade. If the packer / ejector blade is bent, dam- aged, or if blade slide shoes or guide track assembly are worn out, this can cause excessive side loading to the cylinder damaging it internally or bending a plunger or sleeve.
- If the hydraulic system uses quick disconnects (such as on a transfer trailer) or holding / lock type valves, make sure they are properly connected. If not, oil may become trapped in the cylinder causing an excessive pressure build up and damage to the cylinder. This is particularly true if there is a blockage on the retract side of the cylinder and the cylinder is then extended. This could internally intensify the pressure 10 times or more inside the cylinder. (Example: The pump develops 2,000 P.S.I. trying to extend cylinder, oil pressure trapped on the retract side of the cylinder could see 20,000 P.S.I.)
- Do not operate a cylinder at pressures above factory recommended operating pressures (Normally 2,000 P.S.I. unless otherwise approved.) Make sure hydraulic pump is developing required G.P.M., a double-acting telescopic cylinder normally requires 15 G.P.M. to retract properly.
- Most double-acting telescopic cylinders will self bleed themselves of air. Upon installation of anew cylinder this will require cycling the cylinder approximately 10 times to the complete extend and retract positions with no load against it. Check to make sure stages are sequencing properly. When extending, the largest stage should move first then the next largest, etc. and when retracting the smallest should move first then the next smallest, etc.
- On Roll Off units, if the Lift Cylinders are not completely extended when a container is being pulled onto the hoist, the lift cylinders may be pulled open by the weight of the load. Then as the container is pulled over center, the cylinders will be forced closed until they hit the column of oil inside the cylinders causing a sudden pressure surge. If the lift cylinders are pulled open by the load, they should be extended with the control valve to fill them with oil before pulling the container on the rest of the way. Care should be taken if moving a Roll Off unit with tilt cylinders extended, avoiding sudden stops or jolts.
- On Roll Off units dropping off a loaded container, feather control valve to avoid any pressure surges in the reeving / cable cylinders as gravity pulls the container to the ground.
- On Roll Off units, if the container is not evenly loaded and is heavy on one side, the lift cylinders may mis-stage. When the plunger / sleeves attempt to correct themselves, there may be a sudden pressure surge, possibly damaging the cylinder.