Rice Lake Intercomp SW™ Deluxe Portable Vehicle Scale - Manual (Page 30)

SW Users
REV G, February, 2000
30
Vertical Center of Gravity
Q: How do I find the vertical C.G. point?
A (part 1): Using an Intercomp SW scale you can find the vertical C.G. this way:
Measure the wheel base and track. Longitudinal and lateral centers of gravity will be
measured from the center of the tire contact patch; use the center of the tire for the
track, and the center of the hub for the wheel base. The scale will use the left front pad
as the reference point for these calculations. Vertical C.G. will be measured from the
center of the wheel hub. Use inches to the nearest tenth of an inch.
Scale the car normally. When you have all four wheel weights on the display press the
“ENTER” key. This pulls up the features menu. Press 2 for the vertical C.G. point.
Type in the wheel base and press “ENTER”. The longitudinal C.G. in inches will be
shown.
Raise the rear tires. You want to raise the rear end about 1 inch per 10 to 12 inches of
wheel base.
An example: A 105 inch wheel base is a little less than nine feet, raise the rear end
nine inches. Do this by raising the mounting surface of the scale. This could be a
large block or some sort of support rack. When the car is on the scales and rocked in
to settle the bushings press enter. Type in the distance you have raised the surface of
the scale and press enter.
Done!
The first line shows the height of the vertical C.G. above the front wheel hubs. Line 1
shows the longitudinal C.G. when the car is flat. Line three shows longitudinal C.G. with
the car on an angle. It is this change along with the slope angle and the total weight
that is used to calculate the vertical C.G. location.
The last line is just the values you entered for wheel base and the amount you raised
the rear axle.
Add you hub height to get vertical C.G. above ground.
A (part 2): This will require a little work with a calculator.
First some explanation is in order. If you could just lay the car on its side you could just
measure the vertical C.G. directly. This presents some practical difficulties. You must
use a more indirect method.
Cont’d on next page