Sometimes our AD trucks need to be raised on a hydraulic lift to do work on them.
I am blessed with having a commercial Rotary 7500 lb hydraulic lift in my outbuilding.
This is the professional "asymmetric" style, which allows the vehicle to be positioned rearward a bit, so that the driver door can be opened without hitting the driver's side lift column. The lift handles this for to rear "asymmetry" by having 2 short adjustable arms that go under the front of the vehicle, and two longer adjustable arms that go under the rear.
Usually, you are suppsoed to try to place the front arm "pads" under the frame rails as far forward as you can. On an AD truck, that would mean basically just behind the rear mount points for the front springs. (You can't go further forward because the springs block access to the frame rails, obviosuly).
But on my 55 AD truck with its custom dual exhaust pipes, the pipes actually block off access to the front frame rails in that area. I need to place the pads a bit further aft on the frame rails I guess, probably aligned with the front edge of the cab doors.
I have calculated that the center of gravity of the truck is almost exactly under the middle of the door:
According to the factory manual data, the weight disribution of my specific AD truck is 57% front axle, 43% rear axle. The wheelbase is of course 116 inches. That means the center of gravity is .43 x 116 inches = 50 inches back from the front AXLE. That places the c of g right under the center of the door.
So I am not super comfortable with that little distance from the pads to the cneter of gravity (if I could get them right near the rear mounts of the springs, they would be several inches more forward).
Have any of you who work in automotive shops, or that have your own lift, run into something like this?
How have you addressed it?
Or, am I worried too much - as long as the pads are somewhat forward of the c of g, and I don't exert huge downward forces on the front of the chassis, am I ok?
Jim G
