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

On Fri, 16 Oct 2009 16:56:55 +0100, Stephen Mawson wrote:

Secondly, I wonder whether there might be a lack of lubrication in the
motor/gearbox, grease having gone stiff etc.

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.

--
Cheers
Dave.

"Stephen Mawson" wrote in message
...
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



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

on 16/10/2009, Stephen Mawson supposed :
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.

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.

--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk

On Oct 16, 5:02*pm, "Dave Liquorice"
wrote:
On Fri, 16 Oct 2009 16:56:55 +0100, Stephen Mawson wrote:
Secondly, I wonder whether there might be a lack of lubrication in the
motor/gearbox, grease having gone stiff etc.

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.


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

On 16 Oct, 16:56, "Stephen Mawson"
wrote:

Two questions: firstly, does anyone have any experience of the failure modes
of these motors?

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.

"Andy Dingley" wrote in message
...
On 16 Oct, 16:56, "Stephen Mawson"
wrote:

Two questions: firstly, does anyone have any experience of the failure
modes
of these motors?

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.

Fix the tight spot!

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