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Deep-Groove Ball Bearing 020.jpg
686 viewsUnleaded 4340 pre-hardened (Rc-38) steel is used for the gear material. These class 11 gears run dry, & have excellent wear resistance. I machined the gear blanks & the split tapered sleeves in the same setup. This insures that all gear tapers & all sleeve tapers will match. North Shore Gear & Tool cut nine gears plus two additional sizing gears that are .0002 over & .0002 under nominal size.Jim Allen
Deep-Groove Ball Bearing 021.jpg
578 viewsThis tool which moves left to right on precision ground roller ways allowed precise measurement of the correct gear mesh. It was used to determine the correct spacing of the bored holes in the engine mounts.Jim Allen
Deep-Groove Ball Bearing 022.jpg
592 viewsThese jig bored engine mounts locate the concentrically ground (inside & outside) full hard (O-1 tool steel) front ends at the correct gear locations. The three holes are bored to the same size as the ground front ends, at the same time, in the same setup, insuring squareness in both axes at the same time. The front ends are easily slipped into these holes because of the two jack screws located between the four flat head clamp screws seen in the top photo. The eight visible through holes which allow fastening of the front ends, the crankcases & mount together, plus the four clamp screws, give one very rigid unit when all the alloy steel screws are tightened to 50 in lbs of torque. Jim Allen
Deep-Groove Ball Bearing 049.jpg
971 viewsTwo .8966 or .9467 cu. in. engines are precisely located in the bored mount to give the correct gear mesh. The four flat head screws visible between both head pipes tightly clamp both front ends in place. The two set screws between the flat head screws are jack screws which allow the front ends to slip easily into the mount. Precise allignment of the engine lugs & the mount lugs is done in a setup master to insure perfect alignment of both.Jim Allen
Deep-Groove Ball Bearing 050.jpg
1651 viewsThe gear ratio is 1 to1 in this setup. The torque & HP are doubled & the rpm's stay the same (minus any gear loses). Properly designed spur gears typically have efficiencies greater then 98% (Dudley"s Gear Handbook; 2nd edition; chapter 12). At the center output shaft the HP is 14.6; the torque 460.8 in oz; & the rpm 32,000. Total weight of the pictured unit is 5 lb 12 ozs. The flywheel has been removed from the center gear for clarity of the gear mesh. Both motors rotate clockwise with custom made inverted drum valves & the propeller shaft rotates counter clockwise allowing the use of available left hand propellers. Full blade area 2170 propellers, with 7.125+ inches average pitch, are being used with this setup! Jim Allen
Deep-Groove Ball Bearing 051.jpg
1050 viewsSide view of the geared twins. The engines fire alternately & with the gear wine they sound like a turbine. Geared twins set up this way require that both motors turn clockwise. Reverse rotation inverted drum valves made this possible.Jim Allen
Deep-Groove Ball Bearing 052.jpg
1136 viewsTop view of the geared twins. Jim Allen
Deep-Groove Ball Bearing 053.jpg
846 viewsBottom view of the geared twins. The engines are set up on the dyno before being coupled together. These motors are running in a reversed direction, & are tested that way on the dyno. This is possible because the load cell used is a tension or compression model. Also, the inverted drum valves used for induction are designed to run in the reverse direction.Jim Allen
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