Matt Whiting wrote in message ...

Typical worm drives
with a small worm and a large worm gear for a large speed
reduction and large torque gain will be the least efficient,
down around 5%, IIRC.

You are saying that 95% of the power is lost in the gear set? I find
that really hard to believe. If you put 100 HP in and lost 95HP in the
gears, that amount of heat would likely melt them down in short order.


Yes, it would. I suggest that you avoid worm drives for transmissions
that handle 100 hp continuous duty. Worm drives are used where you
need a huge torque increase and can afford a huge power loss better
than you can afford the space complexity and expense of a planetary
gearbox or a battery (Damn it's late at night what do you call these?)
of spur gears.

Typical worm drives are very low speed, or have a very short duty
cycle. In most of the systems I have seen the worm only turns
at a fraction of an rpm in continuous duty (IIRC 1/15 rpm is common
for the worm in a telescope clock drive with a worm wheel with 96 teeth).
When slewing the telescope they may turn several rpm but only for
a minute or so. If those worms were run continuously at a few
hundred rpm they would certainly coke out the grease in a couple
of minutes.

There are some big-assed worm drives that do things like rotate the
turrets on cranes fairly quickly but they operate intermittently
and that HUGE worm wheel soaks up and dissipates a lot of heat.

I am less than 100% certain of the 5% figure, but will stick by it for
now.

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FF