Here's my very glazed over and simplified explanation of CM hoists. An
electric motor that is small enough to be usable for the application (1/2 - 2 hp in the case of most Loadstars) spins really fast and then there is a very large gear reduction to give the
hoist the necessary lifting
power and as a trade off makes the chain moves relatively slow (8 - 32 feet per minute is normal, but CM has hoists up to at least 100 feet per minute). There is a very strong brake that holds the shaft that the chain rotates on in place. It is normally engaged and only releases once
power is applied. It can be removed manually, but it is a process and because of the gear ratio the chain still doesn't move very fast (with no load applied of course). In every model I've worked on one
leg of the input
power is transformed down and sent back out to the control device (the amount varies but 24VAC and 48VAC are common control side voltages). Because of this, if a the motor is already supplied
power you can use a
pickle (Which is kind of a glorified three position
momentary switch) to operate it, but more complex controllers that control both the supply of
power and movement direction of the hoists are more useful and safer. In the case of a 3
phase hoist the motor will spin in either direction depending on the order of the phases (ABC vs. CBA) because of this it's very important that the
hoist controller can only tell the
hoist to move
in one direction at a time.
Fun facts I've learned about CM hoists:
The speed of most CM hoists is actually dependent on frequency not
voltage (there are variety of
power configurations available) because of this a
hoist that CM sold in the US (60 Hz) as a 16 FPM motor will run at ~13.3 FPM in Europe (50 Hz). The difference matters, trust me.
A model L 1 ton
hoist is for all intensive purposes the same
unit as a model R 2 ton
hoist except the model R has a hook with a pulley allowing it to be a double reeved
unit (speed is cut in half, capacity is doubled) and a suspension that's slightly upgraded for the additional capacity. This holds true for many other models of CM hoists.
Lastly a story that we tell in our motor shop but I have not been able to personally confirm. On the load protector in about 8 different languages is says essentially "do not disassemble, contents under extreme pressure." Well at the CM facility one of their shop techs decided since he worked for the manufacturer he didn't have to listen to the warning and he started to disassemble the
unit. Soon after he started to split the load protector it released the pressure by means of launching half of the load protector into the ceiling leaving a perfect imprint of the "Do not disassemble" warning. The story says they never repaired the ceiling but left it there to remind other techs to read the warnings.