ausTIN CANs 2158 | 2023 Build Blog

Bumper Mounting System

My team uses a spring loaded bumper latch to secure our bumpers. When the bumper is pushed down, it is locked in until the release lever (the tall thing sticking up) if flicked.

The bumper latch unlocked.

The bumper latch locked in.

In addition to these, we used some slide-in dovetails to further support the bumper. This was also done to support it per 8" according to bumper rules. The holder is bolted directly to the frame-rail while the slider is connected to the bumper plywood. Both of these pieces are 3D printed PLA at 45% infill and 6 walls. The holder breaks occasionally but not often enough to be a problem.

Picture of dovetail support

We also use 3D printed corner brackets to further support the bumper. This reinforces the bumper corner to the frame, which reduces the lateral forces on the other mounting components.

Photo of bumper corner

Final bumper latch

The lever was originally much smaller (see below) but it was changed in order to easier access them next to the bumpers. The lever was also originally PLA but would break under the upward force of the bumper, so it was later changed to polycarbonate. The front plate of the latch is aluminum in order to bear the load of downward force on the bumper.

The small lever.

The pin is a 1/4-20 bolt with an aluminum spacer attached. The spacer was originally 3D printed but was unreliable so we switched to aluminum. The pins and dovetails are attached to the bumper by T-nuts in the bumper plywood. The mounting holes are patterned to allow for flexible placement of the bumper latches and dovetails.

T-nuts inside of bumper plywood.

The full constructed bumper latch.

The spring is cut down and bent to fit into the bumper latch and lever, it is not used out of the box (see below)

Picture of bent spring

Picture of where the spring goes in the back plate

Bumper Latch CAD file: Onshape

Link to spring: McMaster-Carr