Air Pressure Multiplier

[Richard and Rhonda]

This little , 10 x 4 x 4 inches, device takes air from your coach supply and doubles the pressure. It has been mentioned on the forum before. It is a convenient way of providing the higher pressure needed to inflate your front tires to 120 psig. Hard to get there with just 120 psi max from your engine compressor

Newell sells them for $258.

How does it work? Great !!!!, No, seriously, the concept is simple. Pressure is measured in lbs per square inch, so if we had 50 psi pressing on a disc that was 3 square inches in area then that would equal 150 lbs force. If we coupled that disc to one that was only 1.5 square inches in area then it would exert 300 pounds force. That's how the multiplier works. The incoming air presses on a piston which is coupled to another piston of half it's area. When the pump reaches the end of it's stroke, the air is released on the incoming side, and a spring returns it for the next stroke. It builds pressure on the outbound side with each stroke. So if the incoming pressure is 100, the pump is capable of producing 200 psi. Of course the pump does not produce a large volume of air, but you don't need it for topping off the tires. It does have a regulator so you can control the maximum pressure out of the multiplier.

At $258 I could have certainly bought a nice pancake compressor capable of running at 150 psi. I already had a compressor for the garage, plus you need to actually have the compressor on the bus
So I went for the more expensive but elegant solution. With the engine compressor, aux compressor, and the 12 volt compressor already on the bus, I didn't think adding a fourth was the right thing to do.

Before the multiplier, it would take about ten minutes of fiddling to get the front tires up to about 115. That included bleeding the system air down and only inflating when the sytem pressure was at it's max. With the multiplier, it took all of two minutes to top off the tires. Sweet !!!