BOB NEAL'S COMPRESSION UNIT, U.S. PATENT NO. 2,030,759

patented February 11, 1936

At various times I have posted design concepts at this page that were inspired by Bob Neal’s patent, but really they were my idea.  I have decided now to post Neal’s patent here and let it stand on its own.  It was not only built and tested, it was shown to the chief patent commisioner in Washington D.C., who according to Floyd Neal was Garrett Whiteside of Arkansas.

 This page is dedicated to Bob Neal and his son Floyd for being bold enough to take a self-fueling air engine to Washington D.C. instead of giving up when the patent office said it couldn’t be done.  Because of the trouble he went to, we have evidence that the self-filling air tank is real.  Since they didn’t want to give him a patent anyway, any failure of his working model to measure up would have certainly resulted in a final refusal.  But the patent was granted.

 It has been suggested that perhaps this patent is complete as is.  It probably isn’t, but it might be very close.  The only discrepancy we know of for sure is that Floyd remembers that the valve or some part of it had a long tapered shape.  The patent doesn’t show this.

 Take note that the patent mentions an external source of pressure augmenting the pressure derived from the compressor cylinders.  This might be a key to Neal’s secret, or it might be for the benefit of the patent office so they wouldn’t call it a perpetual motion machine.  I know nothing about his external pressure source, but when I try to design compressors in tanks that are mechanically operated by tank pressure or an outside high pressure source, I always run into the same wall: the pressure that is a benefit pushing an in-tank piston one way is very much a nuisance when the piston wants to go back the other way.  There might be a way around this, but for now I’ve returned to Bill Truitt’s “keep ‘em separate” principle.  Gizmos and gadgets in the tank are fine fuel for the imagination but if air pistons can do it, then so much the better.  See my new web page The Equalizer for information on how I now believe this should be done.

 As for how Neal’s patent could have worked without major elements added or left out, here is my current theory.

 The main difference between his compressor and conventional compressors is not the equalizer—the double check valve in the tank—but the compressor configuration itself.  He shows what is essentially a 28-cylinder compressor the size of a car engine, although he ended up using only half that many cylinders and still had plenty of air going into the tank when he used the device to operate an engine lathe.  But why 28 or 14 cylinders?  Most compressors use as few cylinders as possible.

 Neal’s cylinders are evenly spaced around the crankshaft and the engine cylinder is on the same shaft.  In this way, not only is the usual compression load divided into small bites, but the wave going out of the tank has the same fundamental frequency as the wave coming in, and the air going into the tank is going to have an acoustical hammering effect at the closed end of the intake pipe where the check valves are.  I suspect that high pressures will build up at that point.  It’s a fact that acoustic effects are accentuated or “tuned” in motorcycle tailpipes by using the right length and shape of tapered exhaust pipe.  This is used to supercharge fresh atmosphere into the hot cylinder by fully blasting out or scavenging the spent gases after the power stroke.  It vastly increases the power of the 2-stroke engine. 

 Based on what I’ve read about acoustic power devices, only the peak of the pressure pulse in Neal’s hammering intake pipe will make it across the first check valve.  This will result in pressure building up in the space between the check valves until suddenly in a blast, the contents of that space will enter the tank en masse, leaving behind a depression or low pressure zone for a split second that will help induce the next bit of air.

 There is no reason to doubt this is possible.  There are water pumps such as the Fluidyne and the ABCO by Roy Phillips which use only heat between two check valves to pump water in this way.  I once had a toy boat with a coil of aluminum tubing on deck, and both ends of the coil in the water at the back of the boat.  If you fill the tube with water so there is no air in it, put the boat in the water and light a candle under the coil of tubing, the boat will take off across the water sounding like a machine gun due to alternate outwards blasts of steam and inward intake of fresh water.  The person who made these boats lives in Oregon and is acquainted with a physicist who is an expert on pulsejets.

 My advice to anyone who gets hooked on the Neal Tank concept is to build a small model of exactly what the patent shows, and try it, before trying to design improvements.  That is the path I wish I had taken in 1988 when my work on the equalization engine was interrupted by my discovery of this groundbreaking patent by Bob Neal.

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