Fire vehicle installation
Radio installations in specialty firefighting vehicles are challenging enough, but this one’s a real hummer.
Every mobile installation carries some minimum requirements, but some installations require a bit more thought. Every installation requires planning and some time with the users to ensure that you meet their needs, that safety items are covered and that aesthetics are reasonable. This article describes some pitfalls to avoid using as an example a recent installation in a piece of special-purpose, fire-response equipment. Although most of this discussion is targeted toward police, fire and EMS vehicle installations, many of the principles apply for commercial fleet dipatch vehicles as well.
Safe inflation – Passenger safety should be your number-one priority. Examine the manufacturer’s technical bulletins or contact the dealer to establish the air bag inflation zone. This is a zone to be kept free of equipment or mounts so the passive restraints (air bags) can deploy as designed. Anything placed within these zones poses a potential danger to the occupants of the vehicle. The airbag could deploy and strike equipment, thrusting it violently aside and into an occupant, with resultant injury. Or, worse, equipment within the zone could puncture the airbag and render it useless. Both alternatives are unacceptable.
Heavy metal – Equipment mounts have become more problematic as vehicles have become lighter and smaller. Reinforcement plates for the underside of floor or firewall mounts should be considered when large arrays of equipment are to be mounted on a single pedestal. Even fairly thick aluminum can be roughly formed with a rubber mallet to provide a sturdy mounting surface following the contours of the underside of the vehicle floorboards or the firewall. Some police patrol officers also insist that equipment be moveable so that they can quickly exit the vehicle from the curb-side door in an emergency. This type of mount should still have a positive lock to prevent loss of the equipment, or injury to occupants, if a sudden stop or collision should occur.
Distributing the juice – Electrical safety is next on the list. I have always strongly recommended running positive and negative lines from the battery and fusing them at each end of the line. This is a bit more trouble and more expensive, but it allows greater safety and the option to bond the power line to prevent sneak circuits. Running power lines underfoot to the trunk requires protection from abrasion; running them through the overhead requires bracing to prevent sags. All controls should feed to a central point. This is the pay-off from your planning and discussion with the user. A central control point may be hard to achieve with multiple control heads, but it improves operator safety.
A clean look – Aesthetics of equipment installation may seem a strange concept at first, but if you think about it, it makes sense. Fabricating a rack for mounting multiple control heads, for example, not only improves the “look” of the installation, it protects the equipment cables from damage. If you are lucky, all of the required equipment will be installed at one time, allowing for a single dc power run with fuses mounted and marked and control and power cables laced together and tagged at both ends. Not only does this look professional, it aids in any future troubleshooting or equipment repair.
A humdinger of an installation To demonstrate this point, Photos 1-6 show the integration of form and function in the Anchorage Fire Department’s new “Brush 2” off-road firefighting vehicle. Based on an AM GENRAL HMV (hum-vee) from Danko (www.danko.com), this fire truck is designed to go off road to knock down urban brushfires. (If you have not been to Anchorage, you may be surprised at the amount of forestation within the city.) The vehicle is equipped with a Motorola trunked radio system, a cellphone and the standard siren/lightbar needed by emergency vehicles. The vehicle carries a crew of two-a firefighter and an engineer-so reliable communications is critical to crew safety.
Photo 2 on page 50 shows how the hood lifts forward to expose the engine, which is mounted partly in the crew compartment. The engine compartment is both open and relatively unprotected (Photo 5 above), so it makes a poor choice for mounting communications equipment. The engine mounting takes up considerable room, and with the battery container mounted right behind the engine, space is hard to find. To further complicate matters, the cab roof is low (no doubt a holdover from the military specification for the vehicle). While the design does aid the firefighters while off-road, it almost certainly rules out a roofmount radio or control panel. The areas behind or under the seats are poor choices for an easy mount as well.
The radio shop has done a good job in mounting the communications equipment where both crewpersons can operate the controls and still maintain visibility of the road. The power cable is routed under the cowling and mated up to the battery with nothing to snag or catch as the crew enters or exits the vehicle. Bonding is good, and necessary in this instance, because the truck is equipped with a 305-gallon water tank and small gasoline powered pump. The roof-mounted antenna and lightbar is clean, leaving no cables to snag tree branches while off road.
Plan ahead, talk to the user and run power cables for both sides of the dc feed, with fuses on each end. Take the time to bundle and mark cables and fuses and document the installation, and the end result is a reliable, professional installation.