FLEXING AND VIBRATION OF TRUCK COMPONENTS
19 Oct 77
1. Field users are submitting a number of EIR's and Suggestions to install brackets and braces to prevent components
from failing, leaking, rubbing, or some other malfunction. The function of a bracket or a brace is to hold, to support, and to
prevent relative movement. These items do this by transmitting forces from one component to another. The key to
installing correct brackets and braces is to know why you're wanting a bracket or a brace and to know how it relates to the
rest of the components.
2. Remember how uncomfortable it was to rest your weary head up against the side window when traveling in a car. The
car seat, supporting your body[ and the side of the car, supporting your head, hid different manners of flexing and
vibration (different in frequency, direction, and amount of movement). Therefore, you had to either lay your head down on
the seat or add a wadded-up coat between your head and the side of the car to take a nap. Your body and your head had
to either vibrate together in the same manner or your head had to be dampened and supported to be comfortable.
3. Now, let's apply this idea to heavy trucks and equipment having large, heavy components installed on the main frame,
cab or operator's compartment, and body. The wheels and axles bob up and down, following the irregularities in the road
or terrain. Tires and suspension dampen these vibrations and shocks transmitted to the main frame. Next, the main
frame receives and further dampens vibrations through frame flexing and twisting and the mass of the frame. Finally, the
mounts of large components further dampen and reduce the road shocks and vibrations by flexing slightly. So you see,
almost everything mounted on a heavy truck or equipment has its own vibrating manner. These all differ from each other,
too. You must either add brackets and braces to components having manners that vibrate alike or add means to allow
movement and flexing without breaking-up during vibration differences. This is the same as either resting your head on
the car seat or wadding-up a coat or other absorbing means between your head and the side of the car to take a nap.
Your head, truck radiators, dump hoist oil filters, fire extinguishers, and many similar parts are in the same situation when
it comes to mounting and bracing under conditions of vibration.