Crankfire Systems ^TM

Welcome to Emory Jones Crankfire Systems ^TM

 Original Manuals and Tutorials

ORIGINAL CRANKFIRE INSTALLATION AND OPERATION

Your new Crankfire unit is a simple rugged and reliable mechanism. Please take the time to read this information and familiarize yourself with how and why the unit works. Doing so will allow you to achieve the best possible performance with it.

First a little background:

I have been involved in building and shooting crank fired semi auto twin guns since the early 90s. I saw a pair of the Calico twin gatling guns (10/22s&M1 carbine) at a gun show. Not being financially in a position to enjoy real full autos, I figured this was a way to come as close as possible. While the Calicos were neat little setups, they were designed more as a novelty item than anything else. I wanted something a bit more serious, larger caliber, higher rate of fire, larger magazine capacity, etc. The first hurdle was to increase the rate of fire from that of the two lobe cams. Yes I tried gears, I could write a book on the drawbacks of that. The next option was more lobes on the cams. But if the guns were to fire alternately, without using the Calico style in and out sliding cam system, (another book filled with grief) no matter where the crank stopped, one trigger was in the fire position or dangerously close to it. So the "floating cam" was born. You will notice that the cam used in the Crankfire floats on the drive shaft within the limits of the radial slots cut in it. This serves two functions. In the single gun application it is part of the safety system, allowing the trigger to go to the down position as soon as the crank is stopped. In a twin gun set up it allows the two guns to be phased to fire alternately and still both go to a trigger down condition when the crank is stopped. Combining the four lobe floaters with twin drum fed AR/AKs etc. I had what I wanted, over 1000 rounds per minute. That is until the semi auto beltfed 1919s came along. I just had to have a pair of these little dazzlers with a crank! Guns designed to run full bore and magazine capacity limited only by my available credit line. The 1919 presented some unique challenges; not much room around the trigger where the unit wouldn’t interfere with something else and no place to mount it, without giving up the optics mount or the T&E mount, but mostly the straight up trigger pull. In short, that is why it is clamped to the buffer tube, and the cam and rocker arm are above the trigger. This allowed me to convert the rotary motion of the cam to angular motion of the rocker arm and finally get straight linear motion of the trigger slide (which the 1919 trigger really likes). I started with the four-lobe cam like the others I had used, and the gun ran quite briskly, but really jerky on the crank. I went to the six-lobe cam primarily to smooth out the crank rotation. This does how ever force you to not turn the crank too fast, it will outrun the gun in a heartbeat. The purpose of the pin type construction of the cam is that it provides the quickest possible "snap" of the trigger, allowing the maximum opportunity for the trigger disconnect to re-engage the sear for the next shot. This brings us to the discussion of crank speed. All full auto and semi auto guns can only run as fast as their particular mechanical design, pitted against the laws of physics, will allow them to. The standard 1919A4 full auto gun is rated at 500 rounds per minute give or take a few. And as I understand it, the full auto, when properly timed, actually releases the striker just BEFORE the bolt goes fully into battery. As most of us are stuck with the somewhat clumsy Lee style semi trigger, that can’t release the striker until AFTER the bolt is in full battery, it is doubtful that the semi will ever reach full auto rate. I think this is why the gun seems to peak at the 460/470RPM point and then starts to actually slow down. It would appear that optimum crank speed is about 77/78 revolutions per minute, and that’s a lot slower than you think it is. In all things mechanical, form must necessarily follow function, but I did want the Crankfire to look as "right" as possible when installed on the 1919s. I tried to approach this as if it were being built in the early 1900s for the military, using similar materials, shape and finish. The one concession was the ball lock pin for the trigger roller, but I figured a clevis pin with a cotter key would be a real PIA.

Well on to the step by step procedures.

Legal Notice "All Crankfire Systems Gatling type Secondary Fire Control units, components and design features are covered by U.S. Patent #7,103,999 B2.  Other Patents Pending."

Last Update: Jun 2008