or aluminum disc type. Optional stainless-steel hub and lug covers are popular
to dress up the installation. Tires need
to have a weight rating consistent with
the GV WR of the vehicle, and a visual
indicator of tire inflation needs to be
provided. This can be as simple as a
light-emitting diode (LED) tire cap that
glows when the tire pressure is low or a
more involved system that indicates tire
pressures at the driver’s position. The
brand of tire and tread selection are up
to the purchaser. Select them depending on the availability of service in your
area and the operating conditions you
Another area where you might need to
exceed the standard is the angle of approach and departure. The standard calls
for a minimum of eight degrees, measured from the place where the tire contacts the surface of the road to the lowest
protruding part of the apparatus forward
of the front axle and to the rear of the
rear axle. If you encounter steep hills or
even extreme dips where the fire station
apron meets the road, a long extended
front bumper or rear overhang might
scrape on the street surface. Increasing
the angle of approach and departure will
compensate for these conditions.
The minimum requirement for the
apparatus steering mechanism is
to turn at least 30° left and right for
nondriving axles and 28° for driving
axles. In addition, power steering or
power-assisted steering is to be provided; 30° is a minimal steering angle.
Most modern apparatus are capable of
a 40 to 45° steering angle, which will
improve your turning radius dramatically. An option that might reduce your
steering angle is heavy axle loading
requiring wider front tires, and often
front suction plumbing reduces the
angle to the right side.
Another option you might consider
is a tilting/telescoping steering wheel
that can be adjusted to suit the needs of
various apparatus drivers.
Your selection of a transmission will
be based on the output horsepower and
torque of the engine specified. Most pur-
chasers specify an automatic transmis-
sion with overdrive. Transmission pro-
gramming will depend on the physical
conditions in your jurisdiction and the
driver’s habits. Synthetic transmission
fluid is another option worth considering.
The standard requires front and rear
tow hooks. Some manufacturers can
provide special configurations for heavy
truck towing. Keep in mind is that the
extended front bumper on most appara-
tus is not suitable for lifting and towing.
If you are planning on towing a trailer,
the requirements for a tow hitch are contained in the standard. One consideration
is to match the electrical connections
required for the trailer you will be towing.
Chapter 13, Low-Voltage
Electrical Systems and
Chapter 13 begins with several paragraphs describing the type, size, mounting, and identification of low-voltage
wiring used in the apparatus construction. Switches and circuit protection are
When describing the alternator, there
is not one specific minimum size described. Instead, the standard says that
the alternator must be capable of meeting the apparatus minimum continuous
electrical load at 200°F in the engine
compartment with the engine at idle.
The minimum continuous electrical
load consists of the following:
• Engine and transmission electrical
• Clearance, marker, and headlights.
• Radios at 90 percent receive and 10
• Step and surface lighting.
• 50 percent of compartment lighting.
• Minimum optical warning lights in the
blocking right-of-way mode.
• Current required to operate the pump
and aerial ladder.
• Other critical warning devices or
electrical loads identified by the
The apparatus manufacturer is required to provide documentation of the
electrical system performance tests as
well as a written electrical load analysis,
which will certify that the alternator
meets the standard’s requirements.
Many purchasers request an electrical
load analysis with the bid documentation
for review, prior to awarding a contract.
Also, some specify a specific alternator
brand and output capacity.
LED lighting has made a huge difference in the electrical requirements of
modern fire apparatus. The difference
between a light bar with halogen rotating lights and an LED light bar is substantial. Using LEDs for warning lights,
compartment lights, surface lighting, and
cab lighting has reduced the dependence
on the overall electrical charging system.
That would be my first recommendation
in exceeding the standard: LEDs should
be provided for all lighting.
The vehicle batteries are the heart of
the electrical system. The standard calls
for high-cycle batteries, mounted securely and accessible. It goes on to say that if
the batteries are not accessible with the
cab down, external jumper posts need to
Other than physical size, batteries are
rated in two ways: cold cranking amps
(CCA) and reserve capacity. The CCA
rating must meet the requirements of the
engine manufacturer. With the engine
off, the battery system needs to provide
the minimum continuous electrical load
for 10 minutes without discharging more
than 50 percent of the reserve capacity
and then to restart the engine.
The typical battery system in the past
was two large 12-volt 8-D “bus” batteries.
Over time, most manufacturers have
( 20) This nicely organized compartment has a
vertical divider, vertical roll-out tool boards,
shelves, and bins to organize the equipment.
(Photo by Ron Jeffers.)