User's Guide for Hydraulic Vehicle Lift

Hydraulic vehicle lifts which are used to raise different transportation units can be quite dangerous if handled incorrectly. These vehicle lifts needs to be used very carefully so as to safeguard the user and the people around.

Following are guidelines which should be used while loading, lowering and raising a hydraulic vehicle lift:

Holding Vehicles on Hydraulic Lifts
In order to load a hydraulic vehicle lift correctly you have to be sure of three things- firstly, whether the doors are closed tightly or not, secondly the transmission is sitting in the neutral or not and lastly, whether the engine is off or not. Make sure that there isn't any extra add on such an antenna which can be damaged while the lift is up in the air. Once you are done with it, look out for appropriate locations to set the vehicle in place and put the pads in appropriate position. You might also also need adaptors in certain situations.
Before leaving the place, make sure that you check the blocks which are holding everything in place perfectly. Permanent chocks would be placed at front end of the stand while automatic chocks would be placed at the entrance end which would call for a thorough check that they are securely placed in the air. Be sure of the lift movement and check the automatic chocks at least twice before starting the movement of the system.

Preventions Before Raising
Avoid the mistake of raising the equipment during the start. At the starting point the systems need to be raised only till they are completely supported by the truck lifts and then stop afterwards. Now check out whether the support pads are at the point where they are required and also if the load is not tilted on the supports. Make an extra effort to check the adaptors too. Do the test and check repetitively until you are sure about the perfectness of everything, specially after making an adjustment.

The Final Raising
Elevate the load only when you are sure of the safety. In order to avoid the jerking of load, hoist up the load very slowly and all the more slower with the increase in height. This helps in shifting the position of load and loosening of the seal on the hoist. Consequently, this would make the fluids leak thus, stop and lock the system after reaching at the appropriate height.

Lastly, as they say, prevention is better than cure, be sure of taking proper precautions while working with hydraulic vehicle hoists to be safe and cater safety to your fellow workers as well.

Reviewing Bent Hydraulic Cylinder Rods

Judging Rod Straightness

While dealing with the bent hydraulic cylinder rods, the first and foremost thing is to check the rod straightness. The best time to check rod straightness is the time when the the hydraulic cylinder being repaired or re-sealed. The rods should be placed on rollers the run-out has to be measured with a dial gauge (as shown in the figure below). The rods are needed to be positioned in such a way, that, there is maximum possible amount of gap between the rollers (L). The mid-point run-out time is then measured between the rollers (L/2).

Calculating Run-Out

Though the cylinder rod should ideally be as straight as possible, but still a run-out of 0.5 millimeters can be managed and thus, is considered as normal. Maximum permissible run-out time (measured at L/2) can be calculated using the following formula:

Run-out max. (mm) = 0.5xL/1000

[here, L is equal to the distance between rollers in millimeters]

This can be understood with the help of an example, where the distance between the rollers is 1.2 meters then the allowable or acceptable run-out would be measured as:

0.5 x 1200 / 1000 = 0.6mm

which means, that a 0.6mm run-out is acceptable with the rollers having a difference of 1.2 meters.

Potential Solutions

Most often the bent rods are straightened in a press. At times, the hydraulic cylinder rods can be straightened without any damage to the hard-chrome plating, but in case the chrome is damaged, the ultimate solution is to either replace or re-chrome the rod.

While tackling a bent rod, it is always wise to compare the actual rod loading with the permissible rod loading as per the tensile strength of the rod material and cylinder's mounting arrangement. The obvious solutions in case of rod load crossing permissible load is, either a new rod of higher tensile material or increased diameter of the rod to prevent it from bending.