Hmmm, will have to drag my trailer into the local hobby shop to see about getting some 'parts'... why?
For simple 'test', even if one shatters the gears first time out, there are a few Tamiya worm-gear kits. (fishes for pics/links) Hmmm, seem to be more than a few of them. Here's the run-down:
The 72004 High Efficiency Kit allows 216:1 & 336:1 ratios, uses included RE-260 motor, can take an RE-130/140, $12.39 @ Tower.
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http://www2.gpmd.com/imagel/t/ltamx7204.jpg )
The 72008 4-Speed Kit, with ratios of 1428.2, 555.4, 216 & 84:1, again using RE-260 motor & accepting RE-130/140 motors: $14.69 @ Tower.
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http://www2.gpmd.com/imagel/t/ltamx7208.jpg )
The Planetary Set is also RE-260 powered, can take RE-140, the only in-line unit, and has ratios of 4, 5, 16, 20, 25, 80, 100, & 400:1. At 400:1, its about 15 kilos or torque. $17.99 at Tower.
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http://www2.gpmd.com/imagel/t/ltamx7201.jpg )
Thing is, none are really compact, but Tamiya does make some Mini-Motor sets, $11.99 each at Tower. The 12-speed unit goes down to 209.8:1 (30 rpm) & 946 gf-cm, the 8-speed goes down to 87.8:1, but the 4-speed goes down further; 71.4, 149.9, 314.9, & 661.2:1. All seem to have a 20mm box-height, and use a 030-size 3v motor.
12-speed: (
http://www2.gpmd.com/imagel/t/ltamx0190.jpg ); 8-speed (
http://www2.gpmd.com/imagel/t/ltamx0188.jpg ) & 4-speed (
http://www2.gpmd.com/imagel/t/ltamx0189.jpg )
Then I went looking for just worm gears. Only one found, a stainless one from RobotShop for $45 and change. OW. Gonna have to consider harvesting a heli shaft-drive tail-rotor gearbox, or cannibalizing a 90-degree drive offa sommat...
Then I considered the problem. The shaft has to be stationary at the ramp-end, using a gear to make the ramp-hinge-axle rotate. This requires some re-thinking and perhaps cheap f abrication to 'solve' the problem.
WhiteWolf
Sorry, image-linking dinna work)