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12-28-2010, 05:03 PM #1
Lodge & Shipley Model A Lathe Clutch Adjustment
I have a question on adjusting the “friction” (clutch) on a 20” Model A L&S lathe, and I was hoping that somebody (somebodies?) might be able to shed some light. The lathe is a late (1954) speciman, with s/n of 41590.
The problem is that upon engaging the friction it will sometimes slip out of engagement on its own. It is more inclined to do this while taking heavy cuts, and on occasion has caused some tool breakage.
I’ll try to describe what I think may be relevant in the hope that it may help understand what is going on, and what might be done to improve the situation.
Lifting up on the handle that causes the square control rod to engage the friction. The movement of the tip of the handle is roughly a couple of inches and simply comes against resistance. There is no feel of anything “locking” or going over center.
There is no apparent braking action when the handle is pushed down, just disengagement of the friction.
I have backed out the “Friction Adjusting Nut” shown in figure 2 on page 5 of the manual. One half turn out and there is no engagement when the handle is lifted, one quarter turn shows just a little engagement. Turning the “Friction Adjusting Nut” in from the baseline about on quarter turn results in 100% engagement, that is no matter what you do with the handle/control rod the friction is engaged.
Should I back out the adjusting nut more, then do the proceedure in the manual (page 5)? Perhaps this will find some overcenter or locking function that then gets timed to the friction by turning the Friction Adjusting Nut in??
Appreciate any thoughts that anybody might have!
12-28-2010, 07:40 PM #2
One thing for sure, even on my 1918 selective head, clutch adjustment is not a matter of half and quarter turns, more like 16th turn increments. It's really sensitive.
if you still don't get a solid detent on the clutch lever (and I think you should, all big lathes with clutches I have run have a definite lock-in detent), check the detent mechanism itself. It's hanging right out in the open on my old beast, but it may be a bit more concealed on yours. If the detent ball and spring is gummed up from years of goo, it might not lock in. The 1918 had a detent on a sliding gear that was locked up and had to be taken completely apart to get it to work right.
12-29-2010, 04:02 PM #3
I didn't know that L & S were still building the model "A" in 1954. I have a 20" standard duty model "X" born in 1954, S/N 41697, just a few serial numbers later than yours!
I don't have mine running yet, but it has a "funky" sliding thing that kinda sorta "locks" in the clutch when engaged, on the back side of the headstock. Until I get mine running, I'm not going to be much help here.
There's some others out there that have these lathes, maybe one of them can shed some light on this.
01-03-2011, 12:16 AM #4
Ken, can you describe where your "funky sliding thing" is???
All others with L&S Model A experience! What does/did the clutch feel like???
I haven't found any detent, or anything that look like it. When I disconnect the linkage from the clutch actuating arm that goes into the clutch housing the arm seems to be spring loaded, with detent action, to the disengaged position.
With linkage disengaged from the clutch actuating arm the handle seems to have a limited range of motion, maybe two inches or so at the tip of the handle.
All sorts of threaded adjustment range available in the link rod threading.
Any ideas/comments? All will be appreciated!
01-03-2011, 04:09 AM #5
Mike C once sent me some manual scans on the later jobs. Currently they are big individual GIF files. I'll "print" them to Cute PDF Pro and we'll have a single pdf to have hosted by somebody.
I don't really know if Ken's Model X can be compared to a Model A. Ken's linkage is taking care of forward and reverse internal multiple disc clutches and the linkage has to create a manageable progression from forward to brake (in the middle) to reverse. Its a little funky feeling because it has been trying to accomplish this since 1954.
01-03-2011, 08:38 AM #6
Mahalo nui on the potential later manual, standing by!
01-03-2011, 02:39 PM #7
Chuck, It sounds like your plates are not opening as they should. Most probably gummed up and with weak springs. I have some original springs for the Conway clutch that your model uses (probably). Before I would try anything I would fill it with kerosene, run it for about five minutes while engaging and disengaging the clutch, drain the kerosene and refill with oil. Often the plates with ware groves in the clutch basket and cause annoying little “hang ups” that will engage the clutch but not solidly. My A has a definite “over center” feeling to the clutch.
FYI: as mentioned your lathe uses a Conway clutch, not a L&S made unit. Conway was located down the street and around the corner from L&S and went out of business just a couple years ago. During the early 1980’s I was the set up man there and among other things, I converted all the baskets and hubs from blueprints to G-code.
01-03-2011, 03:17 PM #8
Mahalo nui for your response. Please help me understand how things work. When I disconnect the linkage rod that comes up on the back side of the lathe from the arm that is connected to the shaft that comes out of the clutch housing the arm is spring loaded and moves "up" several inches. This is moving the arm to a "more disengaged" position. This is a smooth movement, without any hangups or feeling of any detents. Is there only one set of springs?
When I move the arm to the engaged position it simply comes up against resistence and then won't go any farther. No feeling of springiness, overcenter or detents.
So,,, the only spring action I can sense, with the clutch actuating mechanism disconnected is to move the working elements toward disengagement. What normally causes an over center condition to keep things engaged until manual interaction causes disengagement?
Also, I gooogled "Conway clutch" and didn't really come up with anything about how they worked.
Again, thanks for the reply, and hope to hear more! Excuse me if I'm slow, but I've never seen the internals of this clutch or been around one working correctly.
01-03-2011, 04:23 PM #9
Chuck, My A was in the process of a bath and new paint when the concrete truck arrived last march for the foundation of the new shop so the A just got itself shoved into a corner for the time being. Sorry for the poor pictures but it’s pretty cluttered in there right now. The first top down pic shows the housing casting with two heavy bosses and a round rod that passes thru the center of each and bisects the clutch center. While not quite obvious, these bosses are not on vertical center to the clutch housing, they are higher. The rod that goes thru them is not just a round shaft but has a relief (think cam) in the middle. I have never had mine apart but that shaft is connected to the rod that goes thru the center of the clutch basket and is the rod that “friction adjusting nut B” is threaded to. Now look at the second picture. As the linkage moves down it turns the shaft and cams over the rod running thru the clutch basket pushing the hub (the big round casting under the friction adjusting nut) to the lathes left. The spring loaded hub moves away and the clutch plates inside the clutch basket are separated. It’s important to understand that there are several plates in the clutch and two separate “types”, One type engages the inside of the driven shaft the other engages the clutch basket, or outside of the rotating clutch. These plates are staggered inside the basket. When the plate are not in contact with each other you have no drive. When the linkage moves opposite, the plates are pulled together by spring tension and the outside of the clutch (being driven by your five belts from the motor) and gives a direct mechanical connection from the outside of your clutch to the inside of your driven member thru clutch plates that are meshed together.
Now since there in movement between the plates, often there is ware in the groves of the clutch basket where the driving lugs of the plates ride. These groves and often old gunked up oil and such can give false drive to plates or slipping, either way. This is really a very easy fix as with marginal skill you can file the groves out and knock off any “burs” on the plate lugs. When Mike mentioned only needing to move the nut a wee bit, this is because in a properly acting clutch all that is needed with solid plates is a couple thousands of an inch. If your plates are taking a lot more it’s a good sign that there are some issues. The good thing is the repair will most likely cost nothing and only take an hour or two. Again, if you take it apart, measure the springs (I believe 6 or them) and I will check to see if I have any on hand. Also possible you only have one big spring, right in the center. If you get into trouble shoot me a pm. Earl.
01-03-2011, 05:23 PM #10
It's built like a motorcycle wet clutch, if you have ever worked on one, Chuck. Basket outside, splined drive inside, alternating friction material (brake or auto clutch lining) and steel plates.
01-03-2011, 05:39 PM #11
OK Guys, we're making progress. First, the pictures match my machine so I sure that we're talking apples to apples. Second, I have a little familiarity with a "Twin Disk" clutch/brake in a Smith & Mills Shaper I've done some work on. Details may be different, but I understand the path of power from the belt driven pulley thru disks to get to the headstock for driving, and through disks to get to the frame for braking.
But, I'm still at a loss as to why the only spring action I'm seeing is to disengage, without any braking, and no spring action that leads to "the plates are pulled together by spring tension".
Am trying to do my understanding before tearing things apart as much as possible, I recognize there comes a time to stop cutting bait and start fishing.
General plan is to try the drain/flush/kero exercize/drain/refill with good oil and see if anything changes. Don't really need the brake function, but would like to get positive engagement.
Cheers, and thanks again for the patience & help.
01-04-2011, 01:06 AM #12
Chuck, Sorry, I should have stated that the "plates are pulled together against spring tension by the operator moving the lever". Not sure how the brake works, best guess it rides against a face in the back of the clutch basket.
01-04-2011, 09:02 AM #13
I wasn't going to jump in without firsthand knowledge, but I was leery of the spring tension holding engagement. Glad you clarified that bigearl. Likely the over center, if not provided by a detent ball or similar is the cam rolling off the flat and closing the clutch plates. if you have it too tight, it's not going to go over center before closing up the clearance, and if it is too loose it will just kind of roll loosely, as there is no tension to hold against it.
01-04-2011, 09:14 AM #14
I'm back in the fog again. On my unit, if I loosen "Adjusting nut B" and try to engage the clutch using the control rod and linkage I get no engagement at all.
If I tighten Adjusting nut B I get 100% engagement. In between I can get both disengagement and engagement by manipulating the control rod, but no positive "over center" or detent feeling.
So,,, I ask the question again, where is the over center or detent action happening?
Intend to do the flushing and reservicing in any case.
01-04-2011, 03:56 PM #15
The instructions for adjustment say to put the lever all the way up (engaged), then commence with the adjustment. Moving the lever while adjusting is going to compound your problems.
Here's what I would try... loosen the lockscrew and turn the nut about a quarter turn counterclockwise with the lever in neutral/ disengage. Now, pull the lever up as far as you can and see if it will stay there. If it does, adjust the nut clockwise until you start to feel it tighten up. Stop and check the clutch engagement, does it go up into a locked position? If so, fire up the lathe and see if it drives the spindle. If not, tighten the nut just a tad more (and I mean 1/100th of a turn, this thing is REAL sensitive to adjustment) and try it again. The instructions say that, if the level slips into place and locks, adjustment is correct.
I can't stress how sensitive the adjustment is. It's just a matter of barely moving the adjuster nut to have it too loose or too tight. If you can't get any kind of a locked position, you may have a stuck detent ball, as I mentioned earlier or something else worn in the works.
01-05-2011, 10:00 PM #16
I think I've got the problem under control. To make a long story short the swivel between the push pull rod from the control rod bellcrank to the bellcrank mounted on the back of the lathe was frozen. The frozen swivel was on the bellcrank mounted on the back of the lathe.
So,,, linkage travel was limited because the swivel wouldn't swivel, and this caused the push pull rod to bend rather than push or pull beyond a point. In other words, the linkage got bound up and simply had a limited range of travel by the time things got to the lever arm at the clutch.
Fix was to take the bellcrank arm out (taper pin driven out), and drive the shoulder bolt out of the swivel, clean up, lube and re-install all. Drained and reserviced clutch lube oil.
Then rig & adjust. Lo and behold, push the lever on the control rod down and you get braking action, lift up and you get clutch engagement, that so far, seems to want to stay engaged. Proof of the pudding will come with some heavy cuts, but I think we're on the downhill slide. Travel of the control rod lever is roughly twice as far as before.
So,,, in summary, I think I'm home free, and appreciate the help in getting there. Now, if I could only find some good published data/parts breakdowns, etc. on Conway clutches I could sleep better. Anyway thanks Earl & Mike C especially.
01-06-2011, 02:36 PM #17
Glad it worked out for ya! Had not considered the op rods binding. If you had to DRIVE the shoulder bolt out, that was definitely the problem. Do let us know how it goes when you start making chips.
03-08-2011, 05:15 PM #18
Final report is that the clutch now stays engaged and it takes positive force to get it to disengage. The push pull rod was bending due to the frozen swivel joint, and in doing so became a spring trying to disengage the clutch. Take out the storing of energy in the system and all is well. As a side benefit once the clutch was readjusted the brake now works when you push the handle down!
Mahalo for all who chimed in, your inputs were valuable!
03-08-2011, 05:34 PM #19
Great news, Chuck.
03-09-2011, 06:12 AM #20
Chuck, Glad it all worked out for you. I’m framing the final wall on my new shop this week and tying to decide which side of it my Model A will sit on, either the active new shop or the old one. Not enough space for all the toys. Glad I was able to help, most time I am just in need and not able to contribute. Earl.