Garage roller door: electric motor

[Stephen Mawson]

My garage door, now seven years old, is the roller kind made of aluminium segments, with a long thin electric motor inside the roller. The motor seems to have been losing power: it will lower the door easily but is very slow at raising it and stops when there is a slightly tight spot in the vertical slides. The manufacturer's advice is of course to change the motor at a cost of £300 plus. The normal output speed at the roller is about 10 rpm so there must be some sort of gearbox inside the roller with the motor. Two questions: firstly, does anyone have any experience of the failure modes of these motors? It seems odd to me that it simply lacks torque. Secondly, I wonder whether there might be a lack of lubrication in the motor/gearbox, grease having gone stiff etc. Does anyone have experience of that? I would take it down and examine the motor, but that is not at all a one-man job.

Many thanks,

Stephen

[Dave Liquorice]

Possibly but I'd look at lack of lubrication of the whole system runners, hinges between segments etc. It drops OK 'cause it has gravity to assist but opening it has to over come gravity and all the little losses in bending and sliding bits against each other.

[Andrew Mawson]

aluminium

vertical

failure modes

motor/gearbox,

Stephen,

The slightly larger ones fitted to the roller shutters of my shops have one run winding, and two start windings for the different directions, with a common capacitor. I can imagine that if the capacitor goes low C the starting torque will be reduced. The gear boxes are epicyclic and concentric with the motor. I think that door was in when you moved in, so is quite a few years old, so it's quite possible that the grease has spread away from the gears and been flung out of position.

AWEM

[Harry Bloomfield]

on 16/10/2009, Stephen Mawson supposed :

If it is like mine, you could run it all the way down, then unhook the drive roller from the door. Once unhooked, the roller frame plus motor etc. can be lifted down - leaving the door still in place.

[NT]

Clean everything out rather than lube it. Lube should normally only be used in the motor bearings and gearbox, if you lube oen external stuff it will only collect muck and get stiff quickly.

NT

[<me9]

I've installed two of that type of door in the last couple of years, one was slightly wider than the other, and has a spring to assist the opening of the door. This required pre-tensioning of the spring as part of the commissioning. That door certainly opens easier than the other one.

Perhaps the spring needs tensioning? However, the spring seems to be integral with the motor within the roller.

[Andy Dingley]

Hideous things: I'd never have another, if I had space for a side- mounted standard motor.

My first problem was overheating and a dead winding. I've also seen the epicyclic gearbox break, so that the planet carrier could wobble and let the gears slip over the annulus. It then "worked" in a one step forward, two steps back way and gave much of the appearance of losing torque.

[John]

Fix the tight spot!

[Stephen Mawson]

I've bitten the bullet and had the motor replaced. It was rated at 250 watts, 17rpm and 40Nm torque (figures which seem to imply an efficiency of about 35%). It was about 60 cm long and only about 5 cm in diameter with no sign of any gearbox.

It goes against the grain to admit it but I have so far been unable to get it apart to examine it in more detail.

Stephen