VIAIR Air Compressor

The air compressor I'm using is a VIAIR model 550C. This compressor

is rated as 100% duty cycle @ 100 psi. The maximum working

pressure is 150 psi. The entire unit weighs about 18.5 lbs. A heavy

duty compressor like this one offers several advantages over

smaller units. It can be operated continuously as opposed to

other models which require significant downtime to cool off. Also,

it fills the storage tank much quicker, which requires less use of

the compressor each day. The ratings of the fill rate are given

for a 3 gallon storage tank. Although, these numbers would be

slightly lower for my 2½ gallon tank.

	0   -  120 psi	1 minute 56 seconds

	0   -  150 psi	2 minutes 50 seconds

	110 -  145 psi	55 seconds

To control the power of the compressor, I mounted a switch in the

dash. Pressing the switch will send power to the compressor, and

in turn, fill the storage tank with air until it reaches 145 psi. At

this point, the pressure switch automatically shuts off the

compressor.The switch is directly below the Autometer air

pressure gauge. The switch and gauge make it easy to monitor

the air system's level and maintain an adequate amount of air at

all times. You never know when those horns are going to be

necessary!



The compressor is noticeable when on. It is not loud enough to

drowned out the radio or conversation. But, it certainly can be

heard in the cab. The only place to mount the compressor, where

there was enough room and protection from the elements, was

the bed.

Dual 29" Hadley Air Horns

Obviously, a truck of this size demands a better horn than the

stock one Ford uses throughout their fleet. The only horn

suitable for this is what the "big rigs" use - Hadley. When I

ordered the horns they were just finishing the production of

their new aluminum horns. I decided to wait for them since

installing these horns would take several weeks while waiting

for different parts, etc. Since the horns would be mounted under

the truck, the aluminum was the perfect choice to deal with the

exposure to moisture and other elements that would be more

harsh on a chrome-plated, steel horn. The horns I went with are

two, 29" long units. Finding a spot to mount these under the truck

is not easy due to their size. Most people mount them under the

front doors, right behind the front wheel well splash guards.

Due to the kodiak step motors there was no room here. The only

other available space was an area under the rear of the cab and

front end of the bed.



Using horns of this size requires that an onboard air compressor

and air storage tank be used. The most important thing about the

plumbing of the air lines, besides leak-free fittings, is that the

hoses supplying each horn with air be equal in length. This

assures that both horns will get the same amount of air at the

same time, and give a uniform sound. You can see the maze of

rubber hose that is necessary to feed all of the necessary

components. A brief explanation of the path of the air goes like

this:

1.	The air compressor compresses the air.

2.	The air is fed into the storage tank.

3.	Several hoses extend from the storage tank.

4.	One hose extends to the dash to supply a reading on the air

	pressure gauge (the switch next to the gauge controls

	power to the pressure switch, which in turn, controls when

	the compressor comes on and goes off).

5.	One hose extends to the rear bumper for a quick connect to

	run air tools or fill tires.

6.	The final hoses extends to the solenoid which controls the

	flow of air to the horns.

7.	The solenoid is controlled via a momentary switch on the

	center console.

It is important to make clean and tight connections throughout

the system. If even one connection has a small leak, either the

performance of the horns will suffer, or the air tank will not

hold it's pressure for long periods of time. My air storage tank

appears to lose only a couple pounds of air pressure per week.

Taking time and care when making these connections will pay

off.