Losmandy G-11 RA and Declination Clutch No-Frills Maintenance Guide
Unlike many other popular EQ mounts on the market, the G-11 has a clutch system that does not lock with levers. This is one of the reasons I bought it. When I want to move to a new target (‘slewing’), I simply grab the scope and move it. I’ll need to learn to use the large setting circles better, but I like this system much better than having to use electronics to slew, or having to unlock levers and re-lock them after manually moving the scope. I have the Digital Drive system, without computer go-to. This is my preference, but others choose the version with the Gemini Computer system. Still, the clutches work in the same way.
Clutch clean-up: where are the clear, simple instructions?
I wanted to get my G-11 ready for work in the field, and knew from research online that the clutch system needs periodic cleaning and re-greasing of both the RA and Dec axes. I figured it would be best to simply do this right away, so I looked at the Losmandy manual. It does give instructions, but there are no photos or diagrams, and the description seemed a bit incomplete. Then I searched online. I found several sites that helped me to get the job done, but now realize that all of them went much further into disassembly than necessary, listing all the tools you would need, and taking off the motors, etc. Some also used jargon that newbies might not know.
These are useful sites, and they provide helpful information, if those are things you want to do. But after completing the clutch maintenance, I decided to write my own guide to just the basics. I’ll go into the detail needed by folks who are not at all familiar with the mount, and I’ll do my best to use clear, simple language.
I’m also going to describe my methods of cleaning and re-greasing, not the method. I used the cleaning products in hand that could get the job done, and I used the only appropriate grease that was available in my local hardware store. I did not decide to write this until after I had already cleaned off the old grease, so I have no photos of that, but will describe the cleaning in detail.
How often and why does it need this maintenance?
Some say to do it yearly, depending on how much it gets used. The clutches work by having a thin (nylon?) clutch pad between two planes of metal. The pad is supposed to be able to spin, but not too freely. Grease — from bearings that need it — can, over time, creep into the clutch pad area and cause slipping.
Another consideration after buying a used G-11 is that you may not know what kind of grease is currently inside the mount. There are lots of greases out there (and a lot has been argued about them!) and some are really not appropriate. Some work well where it’s warm, but not so well in the cold; and the opposite might be true. Some break down over time and can be a real pain to remove once they do. I’ve read in many places that this is what happens to ‘white lithium grease’, yet it is often recommended as a good one to use. Finally, I’ve read that some greases do not mix well with others, so if you don’t now what the old grease is, it’s important to do a very good job of completely removing the old before applying the new.
Getting started: what you need.
Not much! First, you don’t need any tools, unless you count your hands and a pile of clean rags as tools. I found that the grease in my G-11 was not too bad. It did seem more sticky than slippery, and there was more on the bearings than there should have been. Since I didn’t know just what kind it was, I decided on removing it in several steps: First, just wiping big globs off with a dry rag or my finger, then a ‘citrus’ cleaner, then Dawn dishwashing liquid, then a water rinse (of the small parts), then rubbing alcohol, and finally, rubbing dry to remove any water left behind from the 70% alcohol I used. Others have used other things. The Losmandy manual just says to use alcohol, but that would not have done the job for me. If I had not been as concerned about removing every bit of the old grease, not knowing what it was, I could probably have skipped the citrus cleaner. But I’ve gotten ahead of myself!
There is no need to take the mount off the tripod. Remove the counterweight bar and the polar scope (if you have one). I started with the Dec axis, but it doesn’t matter.
1. Just unscrew the clutch knob with your hand until it comes off.
Notice the order of what came out. This is weird, actually. According to the manual, the spring washer should be between the clutch knob and the spacer:
“First, remove the clutch knob. Five parts will come off the shaft. Spring washer, aluminum spacer, thin washer, needle bearing and thin washer.”
(from the Losmandy online manual for the G-11)
But I found someone on the internet who says that the mount comes from Losmandy in the order shown in the photo, and that he found it better to place them with the spring washer between the clutch knob and spacer (which is what the manual states). I’m not sure this matters too much, and I’m going to test them both. More on this later.
What does matter is that the small thrust washer goes between the two thin washers, and that these go onto the shaft first.
If your grease is sticky, the pieces may not just slide out, but will come off during the next step.
2. Grab the saddle plate and pull the shaft straight out. You will probably hear and feel the threads on the end of the shaft bumping and scraping a bit against the bearings inside. If the washers, etc, on the bottom of the shaft were a bit stuck inside the housing, hold your hand down there for them to fall onto.
3. Set the piece you’ve removed on your clean workspace, and remove the clutch pad from the shaft. It fits very tightly, so needs to be removed carefully. I had bought spares, just in case these were damaged (a pair of spares is available from Losmandy for $15), but I didn’t need them. I found that pulling the pad off scraped most of the extra grease off the shaft.
The parts that must be completely free of any grease are the clutch pads, and the round plates on the mount between which the pads fit. In a routine clean-up, I would think you might find that others parts don’t need complete stripping of grease, especially if you do it regularly. But since this was the first time, I made sure to get all of the grease out of all of the parts.
1. The needle bearings:
Inside the mount, on both axes, there are two needle bearings; one at the top, and one at the bottom. In my mount, they were sticky with grease and there were also some globs inside between them.
a. I used a dry rag to remove the globs and what was visible on the bearings, then I put some of the citrus cleaner, undiluted, onto another clean rag and worked it into the bearings by stuffing the wet rag inside and twisting it back and forth. The little needles rubbed together and got looser and looser as they spun. I kept this up until it seemed they were as loose as they were going to get. Then I let them continue soaking for a minute or two.
b. I took a clean dry rag and used it to soak up much of the grease/cleaner mixture.
c. I now switched to the Dawn, mixed strong with water, and did the same thing I had done with the citrus cleaner.
d. Another dry rag to soak up the liquid; then a damp rag to rinse.
e. Alcohol was now used to get any traces of whatever might be left. Poured straight onto a rag, and the soaked rag used on the bearings. I went over it for a while, just to make sure.
f. Finally, a dry rag was used to soak up any water left from the 70% alcohol.
The Clutch Plates:
The plates on the shaft and the mount between which the pad fits were not too bad, but just to make sure all impurities were removed, I used damp rags with Citrus, then Dawn, then water, then alcohol, then a dry rag. No real rubbing was needed, just wiping. I also cleaned the shaft in the same way.
The Small Bits:
1. I just plopped the clutch knob, spacer, washers, and thrust bearing into a bowl with a fairly strong mix of citrus cleaner and water and left them for a bit. Then I wiped them with a cloth dipped in the mixture. I worked on the thrust bearing for a while, making sure to get all the rolling cylinders completely free of grease.
2. I rinsed each piece in the sink before plopping them into a strong mixture of Dawn and water. I repeated the wiping, and this time, the thrust bearing needed little time; this was more a rinsing then anything else.
3. After another rinse in the sink, I wiped each piece down with alcohol. For the thrust bearing, I then rubbed with a dry cloth, to get out anything that might have been left. For everything else, the alcohol evaporated immediately.
First, you don’t need much! There is no reason for grease to ooze out anywhere. The turning parts just need a thin coating.
The only places that should get grease are these:
— The needle bearings, both top and bottom;
— The thrust bearing;
— And a tiny bit on the threads that are on the bottom of the shaft, to aid in tightening and loosening the clutch knob.
There may be a different or better way of doing this, but I just used a finger.
The needle bearings inside the mount:
I put a little dab (less than pea-sized) of Super Lube on the tip of a finger, and reached in. I gently spread it out along the needle bearing rollers as far as it would go, and then started sort-of massaging the rollers with two or three fingers. They will roll together freely around the bearing housing, and I did this to them until I could feel that the grease was distributed all the way around, and from end to end of the rollers. I found that I needed another little glob of grease to get complete coverage. But two small blobs allowed me to spread it out without having any spill over the edge of the bearing. I did spill a little, but just wiped it out with a small tip of rag. Any tiny bit of residue left won’t matter, and there was very little left. This method worked on all four needle bearings, both in the RA and Dec housings.
The thrust bearings:
I used the same finger procedure, but needed far less grease. In fact, after spreading it all around the bearing, I needed to wipe excess away with a dry cloth.
This is pretty straightforward.
1. After making sure your hands are clean (something that will need doing many times during this process), slide the clutch pad onto the shaft, all the way until it rides against the clutch plate at the top. This was a bit difficult because of the tight fit.
2. Slide the shaft straight into the housing.
3. Slide these onto the shaft in this order***:
— Thin washer;
— Thrust bearing;
— Thin washer;
— Spring washer;
— Clutch Knob.
***Again, this is the order stated in the Losmandy manual, but not the order I found mine in; and others have also found the spacer and spring washer switched. I’ve tried both now, and there does not seem to be a difference in the feel of the clutch, but having the spring washer on the outside of the spacer may keep stuff from getting inside the shaft housing. Since it is what the manual says, I’m going to stick with this. If someone explains otherwise, I’ll make an update.
Screw the clutch knob on until it tightens everything up.
And you’re finished! (Well, half-way.)
I noticed a definite difference: The clutch can get tighter now, though it will never ‘lock’, and isn’t supposed to. But it is also much smoother, with little ‘stiction’ and no slipping. It moves while I push on it, and it stops when I stop.
I’m not going to go step by step through the process with the RA axis, since it is almost identical. But I’ll include some photos, because it looks a little different.
After putting the DEC axis back together, I just took the RA shaft off with the Dec inside it. This avoided having too many parts floating around, and meant that the Dec axis was not open to the air, and potential contamination, any longer than necessary (though that’s probably not anything to worry about).
NOTE: When loosening the RA clutch knob, remember to hold onto the mount so that it doesn’t smash the motor when it lets go!
Since it was my first time, and since I took the time to take photos, I figure it took me about four or five hours to do this job.