Lister Engine Forum

General Category => General Discussion => Topic started by: BruceM on January 10, 2019, 07:13:30 PM

Title: cold weather gear motor lube
Post by: BruceM on January 10, 2019, 07:13:30 PM
I had a failure of the 5 rpm gear motor actuator which I use to control my projector focus.  Focus control is needed as the Qume Q5 focus is not temperature stable. it's a 24VDC rated little can type brushed motor I operate on 12V.  It stopped working when it got cold, even at 40F the motor would not start.  I use a modifed 2 channel IR receiver to control the gear drive, since I already have IR extender control of the projector.

I took it apart the failed gear motor and found the motor, brushes and commutator are clean, and the motor starts and runs freely at 12v in both directions.

So I'm thinking that the black grease which covers all the metal gears, and the worm drive which is on the motor shaft gets so stiff in the cold that the motor can't spin up.  Spin up is not aided by the two pole commutator. 

I'm thinking of cleaning out the grease and putting a bit of ATF on the gears.  I'm also going to boost the voltage.  I think there's some 19 or 21VDC for the projector I can use. This is not a high stress application and it only runs for maybe 30 seconds a day.  Any other ideas?
Title: Re: cold weather gear motor lube
Post by: mike90045 on January 10, 2019, 09:07:25 PM
I'd worry that the high RPM's would sling the ATF off and then you have dry gears.   What about a silicone lube or graphite, even assembly lube ?
Title: Re: cold weather gear motor lube
Post by: glort on January 10, 2019, 09:40:26 PM

As i was reading I was thinking to myself ATF and then a bit surprised when I read you suggested it.
In my book ATF is a very under rated lubricant. It is thin but has very high lubrication properties.

The only thinkg I'd be worried about is keeping it there but perhaps you could incorporate a small pad which you could put it on to wipe the gears as they moved and just remember to put a drop more on at regular if infrequent intervals.
The grease probably isn't doing much in this instance as it would be never getting hot enough to move into the friction area and disperse itself back to where needed.

A little wiper pad with ATF may be a lot better.
Title: Re: cold weather gear motor lube
Post by: BruceM on January 10, 2019, 10:05:29 PM
I had some 5w40 synthetic motor oil in the shop so used that after taking the grease packed box apart and cleaning it. I needed the spare to compare for reassembly.  I'll see if the gear motor still works when it's 0F. If not, I'll try ATF.  I decided to leave it at 12v for now and see how it goes.

I was wrong before, it's a 1 rpm gearbox rated at 24v.  It has plenty of power on the output. Decently engineered gearbox, all metal gears but the worm drive 1st stage. A bargain.

It sure is nice to have my display in focus.