OT How would you repair this?

[Generatorgus]

This is a drive gear for my camper jack power unit. Evidently a lousy press fit, as the pinion spins inside the larger gear. I had no problem separating them. My first though was to silver solder, as they are both made of steel, but I'm thinking the heat might ruin things. Second thought is a straight knurl and repress it, or maybe pin it.
The company, Rieco, say they don't sell parts and will only sell a new power head at the tune of $315 plus shipping. The unit is 3 months out of warranty.

The large gear is about 3" dia. and is identical both sides. The pinion shaft is about 3/8", that's a guess, I didn't measure them.
The large gear is driven by the motor unit, the pinion drives another gear linked to the worm drive of the jack. The jacks are rated for 2500 lb., this particular jack was on the rear of my truck camper and only lifts about700 lb. or so. Oddly enough it started slipping as I was lowering the camper.
GUS

 

[slick95]

Hey Gus,

If it were me I would go for the Locktite 609. Clean it really good and it may work for you. I've had good success with this stuff.
Here is a link for you...

http://useloctite.com/products/product_details_retainingb76c.php

Gook luck

Jeff

 

[ozzie46]

How about cutting key ways in the gear and shaft and key them together.

Or using an end mill, mill a hole at the intersection of the gear bore and shaft edge and pin it. I say use an end mill because if you try to drill it, the cast iron being softer than the steel shaft will cause the drill bit to wander.
I've also heard that permanent locktite will hold it. I seem to recall reading that is how they hold full size railroad wheels to the axles now.


Looks like Jeff was posting as I was typing this up. :big:
Just my 2 cents.


Ron

 

[gbritnell]

It's hard to tell if both gears are made from the same steel. It looks like the pinion gear could be hardened by the shiny finish. What I would do is make a split ring collet to hold the big gear, bore it out, make a sleeve and then repress the two together.
The other possible option would be to put the two gears back together with Loctite and then drill between the two diameters for a round pin (key). That's only if the two gears are made from the same material otherwise the drill will push off into the softer gear.
gbritnell

 

[crankshafter]

Gus.
Knurl the pinion, add. some 609 and press it in.
Just my 2 c *bang*
CS

 

[jonesie]

i agree with ozzie i would cut keyways and then loctite it. a small keyway on the bore could be cut on the lathe if you do not have broches. jonesie

 

[Florian]

Hey Guys


I guess the small gear is hardened... so a modification is difficult (need for special end mills)

I would try it with loctite. Your not destroying anything when using loctite! Maybe you see that its not working but you din't do anything to the Parts.

Id use rather the 648 than the 609 (has a greater strenth especially on shear forces)
Cleaning it with acetone should be enough...

If it does not work, you can still choose another Way.

Or, if you dont want to do it with loctite, you could go for the solution George proposed.
I would do it almost like george said it but with a difference on the "sleeve".

I would make kind of a flange to screw on the big wheel (beeing centered by the outer diameter of the flange)
The big wheel would be turned to half the thickness from before so the flange can be fitted to the wheel without getting a wider gear...
That way you don't have a double press fit (which can make difficulties when pressing it together...)
But its more work of course...

Cheers
Florian

 

[steamer]

Loctite......it'll be stronger than original.....

Dave

 

[deere_x475guy]

If all the other suggestions fail...you can try this...

• cut down the shank on the pinion gear enough so you can shrink fit a bushing over it
• cut the dia. of the bushing larger than the bore of the big gear for another shrink fit

Shrink fits are better than press fits because you aren't displacing metal like you do with a press fit.

I have done several repairs to shafts using this method. My neighbor is using his Simpicity garden tractor with a repair I did for him that is simular to what you are facing....he used it all season this year with no problems.

 

[Metal Butcher]

Its important to understand that Loctite brand products in the #2 series like 242, 271 etc are 'thread lockers'. And products in the #6 series like 609, 620, 635, 640, 642, 660, 675, and 680 are 'retaining compounds'. The products in the #6 series have shear strength ratings of 3,000, 3,500, and 4,000 psi, based on 1/2" diameter de-greased pins in collars. At those pressures its likely that the teeth would sheer off one of the gears before the Loctite would fail. Depending of course on the size and strength of the gears.

In choosing the best suited 'retaining compound' the gap to be filled is a very important aspect, and without knowing that making a recommendation is guess work.

Gaps, up to;
609-.005 gap
620- .015
635- ..010
640- .007
642- .012
660- .020
675- .005
680- .015

All of the above are 3,000 psi rated with the following exceptions;
642- 3,500
635- 4,000
680- 4,000

Its best to consult with a Loctite representative before making your purchase.

http://www.henkelna.com/industrial/technical-support-5211.htm?param1=type%3Dtechnical|contextPK%3D39994396696615280|

-MB

 

[rcmadness]

Personally I cannot believe that a manufacture would us a press fit for such a crucial application on a jack, especially if the mechanism were to fail and the jack would slip. From what you have said the jack actually slipped when you were letting it down.
With that in mind i would want it keyed or welded to the point it would not allow anything to slip. Locktite or any other chemical bonding agent (i.e. glue) is not something that should be trusted under extreme conditions like a 2500 lb jack would see and have the risk of someone being in the line of fire if it failed.

Just my two cents.

 

[Ed T]

I have used locktite for a lot of things in the past and, generally, it has worked well. That said, it would not be my choice for this situation.A jack is not the kind of thing where failure is an option. It is likely that the big gear is powdered metal and the small one is probably machined from pinion stock and probably is not hardened although it may be harder than the powdered metal gear. In a similar case I had to refasten a steel insert into an aluminum flywheel on an old Wisconsin engine. I drilled three holes on a drill press with ordinary drill bits and pressed 3/16" roll pins into the holes. Yes the holes wandered a bit favoring the softer metal, but I was still able to get a good mechanical joint that has lasted over 20 years. I think I also used some epoxy to stabilize the joint. Of course welding or soldering was not an option here because of the disimilar metals. In your case, I think I would go for pinning and soft solder to stabilize things. If the big gear is powdered metal, it will suck up solder like a sponge so be prepared for that. If it was mine, I think I would pin it in a couple of spots and carefully silver solder it to minimize the HAZ. If the big gear is cast iron or PM welding is probably not an option.

 

[Metal Butcher]

I know that every one posting on this thread means well, and I don't want to sound like I'm criticizing any ones best intentions.

The gears in my trailer jacks are all die cast zinc (cheepo's). They (gears) do not hold the trailer up. There is a very small amount of pressure on these gears whether their hand cranked or driven by a small electric motor, and they do not have a ratchet stop mechanism. They operate a screw just like that on a milling vise. Open a vise part way, install a machinist jack to 'try' and pry the vise open, and you can't. Holding on to the handle (jack gears) makes no difference. The gear operated 'screw' on these trailer jacks is holding the trailer up, not the gears. You could remove a gear on a jack that's holding a trailer up, and the trailer would not collapse.

I would not dismiss the use of Loctite to repair the gear drive in this application.

-MB

 

[rcmadness]

Sorry, I misunderstood the use, when you said slipped I interpreted that the lifting mechanism gave way. That being the case the glue away, the only real concern is that the jack won't lift or lower if it fails then you can deal with it. Devcon has always worked well for me. (Commercial JB weld) :big:

 

[Generatorgus]

Wow, lots of options, THANKS :bow: for all the replies, all of the good. It seems Loctite is the favored method.
I was going to post a better explanation of slipped, but metal butcher covered it quite well.
I'm leaning to the combination of Loctite and a pin, probably a roll pin. Choice is based on simplicity rather than what would be the stongest. I don't have a straight knurler, but I feel it would work better than the cross hatch type I have, also it ain't that sharp anymore and I'm afraid the little pinion gear would get damaged by the pressure required to inprint the knurl. My luck would be that it would be pushed right out of the lathe chuck
Although I'm fairly sure some thpe of hardening is used on the pinion, I tested the pressed in section with a file and it readily bit in, but I will mill a hole rather than drill it just to make sure. I have a pretty good assortment or roll pins on hand, but no decent type of Loctite, but I was wanting to try it anyway. I see it's use mentioned many times in a lot of posts and builds I've been quietly watching here. Sounds like a miracle adhesive.
Many thanks guys, I didn't expect that many replies.
GUS

 

[Generatorgus]

Well I mated up the pinion and big gear, put the in the vise and milled two holes on opposite sides of the shaft. Went well and looked very good, I thought. ??? When I tested the 1/8 x 1/4 lg. roll pins, they fell into the holes, with plenty of clearance. :'(

Confused, but too late to go back, I started looking for something I could use for the pins, without machining something on the lathe. My only 3.5mm drill bit is now a 1/2" shorter.
I checked the dia. of the 4 flute mill and and it is a perfect .125. Other then being a Grizzly acquisition, why such a big hole? I tried the same mill on a piece of alum. scrap, it was a good fit for the 1/8 roll pins. Thinking maybe I should have used a 2 flute mill, I tried a sample cut on the alum. it came out way too big. Was I using the wrong mill for the gear?
GUS

 

[hammers-n-nails]

i wuld suggest that instead of roll pins that rely on a tight fit instead dril/tap suitable size, use a button head machine screw if theres room or a piece of allthead and either locktight it in or smash the threads just a bit so you have to force them a little to turn then cut and file flush.

 

[shred]

Did you pre-drill the holes or just whack an end mill through the material? End mills often wander and deflect on plunge cuts like that, resulting in oversize holes. It's in their nature; the center of the bit has very low surface speed compared to the outside edges and thus cuts less well. So during the cut, the end of the mill says "hey, its easier to cut over here, let's go this way.." only to be held back by the body of the mill itself. The body isn't perfectly rigid so it bends a little in the process and the end of the mill ends up making an orbit larger than it's diameter.

 

[Generatorgus]

i wuld suggest that instead of roll pins that rely on a tight fit instead dril/tap suitable size, use a button head machine screw if theres room or a piece of allthead and either locktight it in or smash the threads just a bit so you have to force them a little to turn then cut and file flush.

The hub is only 1/4" thick and the gear is tight to the back, and I don"t have a bottoming tap, I am going to stick it with the Loctite, which I ordered the other day.

Shred, I think your right. I didn't pre drill, as I got previous advice about the drill wandering while drilling metals of different hardness. I used the same mill to slot a bar the next day, it worked just fine.
GUS