Installation tips for heavy equipment Building your own mounting plate, placing the radio near the operator, using a power buss and taking care in antenna mounting will ensure a successful installation in a road grader and other types of construction vehi

Installing radios in heavy equipment can be straightforward and relatively trouble-free if the installation technician plans ahead, talks with the operator and follows some simple tips. The planning required usually is minimal, including checking equipment system battery voltages and potential mount locations. For example, let’s focus on one type of equipment, a road grader (motor blade), to explore some different installation options.

The grader in this example is used in snow removal and general maintenance work at a large airport. This operating location requires the grader to have a VHF FM land mobile radio, a VHF AM aircraft band radio and a strobe light that operates continually while the engine runs. The operator cab is almost entirely glass and is filled with control lines and levers. (See Photo 1 above left.)

Mounting the radio equipment on the cab’s ceiling is ruled out because some of the equipment operators are short and would find it difficult to reach the controls safely for adjustment. Floor space is almost non-existent, and the seat is spring-mounted for operator comfort. These limitations are not too uncommon, yet the installation is not difficult when steps are taken in this order: first, the radio mount; then, the interconnect wiring; and finally, the antenna mount.

Having ruled out the cab’s ceiling and floor as radio mount positions and with the cab walls being made mostly of glass, it becomes necessary to build a mount location. On the right and left sides of the operator’s seat, measure the distance between the risers (roof supports). Then measure the length of the radio set to be installed. To create a place to mount the R/T unit, we will build and attach a plate on the risers. From mild steel or rigid aluminum plate, cut a section of metal wide enough to span cab risers and to support the radio mount. Paint both sides to improve its appearance and to retard corrosion. Attach the plate to the cab risers with large sheet metal screws. Use at least three on each side if a radio mount will be attached to the plate. Use more screws if the plate itself will hold the R/T unit. (See Photo 2 at the left.)

To hold the plate while drilling screw mount holes (I drill the plate and riser at the same time), use double-sided tape to hold the plate in place. Then remove the plate and attach the radio mount to the plate. Using the tape allows you to check the fit of the radio mount quickly before finally fastening it in place. When you are sure everything fits, screw in the mount and plate, and then attach the R/T unit. Route the wiring down and behind the operator’s seat. Use tie-wraps or cable loops to hold the wires away from pinch points under the seat or where the operators place their feet. Feeding the power supply wires into the battery compartment is fairly simple. Take the time to use a magnetic switch or low-voltage cutout switch in-line to protect your equipment. (See Photo 3 above right.) If you are installing multiple radios, take the time to pull a “buss” wire from the battery supply, bring the radio power wires to a screw block and tie them together. This will simplify troubleshooting and future equipment installations. If you must route wires through any bulkheads, use a rubber grommet to protect the wiring. To seal the grommet, room-temperature vulcanizing (RTV) caulk may be used safely if bare metal is not exposed to the acid excreted by the RTV while curing. Avoid splices near the battery compartment, and use heat-shrink tubing to protect any other splices. When shrinking this type of tubing, use a heat gun. A flame or other open heat source is not safe. Where space is tight, liquid vinyl may be used to protect splices. Avoid using liquid vinyl in high-temperature areas, and always ensure good ventilation during application.

If the radio set requires a control head, use another plate and mount it on the other side of the cab. Use common sense and care in wiring. When aircraft band and land mobile radios are installed in the same vehicle, it usually is necessary to install a filter to reduce interference between the sets. Because of their light weight, speakers can be safely mounted on the risers to be near the operator’s head or on the cab’s ceiling. As with any equipment mounted where it will be overhead, check the mounts at least as frequently as you check the antenna system. (See Photo 4 above left.)

Speaking of antennas… If strobe lights are roof-mounted or if the grader will be used near overhead obstructions, consider building a mount to hold the antenna to the side of the operator cab roof. A simple L-shaped bracket attached to the side or rear of the cab is adequate in most situations. If you mount antenna brackets on opposite sides of the cab, it will help to reduce interaction between the land mobile radio and aircraft band radio systems. (See Photo 5 above.)

Using the engine deck, or motor hood. as an antenna mounting point, even with diesel powered machines, is not a good idea. Vibration and heat will soon cause trouble in antenna systems and cables. Antenna cables can be routed near cab windows to avoid obstructing the operator’s vision. Be careful that the power and antenna cables are not pinched between the cab and engine housing. (See Photo 6 above.)

Building your own mounting plate, placing the radio near the operator, using a power buss and taking care in antenna mounting will ensure a successful installation. These installation suggestions apply to other types of heavy equipment with operator cabs. If the equipment is not provided with a cab, similar methods will work. The difference would be that the R/T unit is placed in a weatherproof box or is protected by a weather hood.

Acknowledgments Thanks to Anchorage International Airport and Tom Eral, Bobbie Frisby, Rich Hittle and the rest of the professional operating crew all working to make our lives safer.