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Author Topic: QUICK $2.25 BELARUS 420A STEERING FIX after shaft bearing disintegration  (Read 2762 times)

damengineer

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Re: QUICK $2.25 BELARUS 420A STEERING FIX after shaft bearing disintegration
« Reply #5 on: January 01, 2018, 10:28:51 AM »
Great post!   A lathe and nylatron stock has saved my bacon many times.  Nylatron is a graphite impregnated hard nylon that works great for bushings.   Especially where abrasion is present in dirty situations.   Even made one for a wear bushing in a hyd cylinder... 

Thanks for posting the info.   
  • MTZ 1220 w/ Kr-34 loader, Belarus 8345 w/ Koyker loader, Belarus 825 w/ Memo loader, White 2-105, Case 1270,
If your not leading the pack, the view is always the same!!

imperial1960

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Re: QUICK $2.25 BELARUS 420A STEERING FIX
« Reply #4 on: December 18, 2017, 05:00:03 PM »
Excellent post!
Belarus 562 4x4 russian loader bucket

Brought Upright

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Re: QUICK $2.25 BELARUS 420A STEERING FIX
« Reply #3 on: December 18, 2017, 03:41:41 AM »
Thanks Haymaker, yep I bet you're right that bronze would be even better. Ha, when I was first thinking of using the scrap poly my Grandfather's ghost was telling me the same thing as he was a metallurgist who worked on developing sintered bronze bearings...but not having any heavy bronze or the time to get some I tried the poly I had on hand & got the tractor back to work in a few hours. Happy to report that, kinda like these tractors, simple & cheap can be good enough for the job, she moves & loads big logs all day & still has no steering play.

I guess the apple doesn't fall too far from the tree, after WW2 my father rebuilt a Model A Ford & drove back & forth from New England to Alaska twice in it. One night on the dirt ALCAN road he came upon a family huddled in their broken down car. A rear axle bearing failed so my dad cleaned it out & packed a greased section of his leather belt in there & got them rolling (slowly) home.

But if this poly bushing ever leaves me stranded I won't try stuffing my belt in that booster box...I'll hold those darn gears together with a poly logging wedge so I can steer home & order up a slice of some 72mm OD bronze bar stock...

Bronze Bearings vs. Plastic Bushings:
https://www.igus.com/wpck/6410/plastic_bushings
« Last Edit: January 14, 2018, 01:33:48 AM by Brought Upright »
  • Belarus 420A

Haymaker

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Re: QUICK $2.25 BELARUS 420A STEERING FIX
« Reply #2 on: December 17, 2017, 09:26:16 PM »
Very nice write up on your repair!! I know some of that nylon material is hard stuff as my neighbor has a lathe and makes stuff out if it often.  But wouldn't say bronze bushing stock stand up better in this application?   
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Brought Upright

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QUICK $2.25 BELARUS 420A STEERING FIX after shaft bearing disintegration
« Reply #1 on: December 17, 2017, 08:55:08 AM »
If you have too much play in your steering booster you can fix it in a few hours for about $2.25 in materials by replacing the booster housing bearing with a bushing made out of a nine square inch scrap of 1.5" thick HDPE (High Density Polyethylene).

A while ago my top steering booster bearing finally failed on my Belarus 420A after over 25 years of heavy loader use. I started heading out of the woods that night after hearing a clunk from the booster area resulting in over a full steering wheel revolution of steering play. It was still reasonably drivable...until the front wheels got jammed up crossing a rocky creek and, with all the slack from the imploded top bearing, the steering shaft skipped a tooth on the booster piston resulting in NO left turning at all. Luckily I only had right turns through some tight woods to get to my road which was the easiest part... the harder part was having to stop along the road shoulder about every 20 feet to crank the front wheels to the left as far as possible with a 5' pry bar...which wasn't very far because the straightest the tractor would go was a slight arc to the right. Ha, this routine got old fast so for the last stretch before my driveway I gladly let the right front wheel bolts scrape the guardrail all the way home.

Naturally I was in the middle of a job that needed to be finished quickly so rather than wait for the parts to arrive to bypass the OEM steering with a ram system I fixed it better than new in a few hours by replacing the failed top booster housing bearing with a simple homemade HDPE bushing. One could also make a bushing out of hardwood in a pinch, especially if you have any Lignum Vitae/ironwood. No joke, Lignum Vitae was used for the prop shaft bearings in many vessels incl the USS Nautilus nuclear sub as well as hydroelectric plant turbine bearings etc. Anyway, if you don't have any Ironwood or 1.5" HDPE the latter can be found for about .25 cents per square inch on eBay etc.

Here's my skinny & 5 pics, your mileage my vary:

1) REMOVE STEERING BOOSTER "HOUSING COVER": 6 bolts.
*BTW, my "regulator screw" got sheared off when the booster bearing failed & the unsupported shaft moved around so I simply replaced it with a long double nutted M16 bolt;

2) DRAIN OIL:
Remove drain plug from lower front of "steering mechanism pipe" to drain hydraulic oil. I lost my seal due to a shattered "housing packing" so my booster oil (& metal shards) drained from here;

3) REMOVE SHAFT:
Leave steering mechanism pipe in place to pry shaft up & out (you don't necessarily have to remove steering mechanism pipe unless servicing lower bearing).
If your steering shaft is hard to remove like mine, which was all bound up with loose ball bearings, shattered races & housing packing pieces, you can pry up through the hole in the frame front starting with the "steering arm" still installed. Heat lower bearing area of "steering mechanism pipe" and/or use more force until shaft budges up. Remove two steering arm 22mm bolts & continue prying up using incrementally larger sockets & bolts between pry bar & shaft bottom until steering arm drops off. Continue with this method until shaft comes all the way up & out;

4) REMOVE BOOSTER HOUSING:
You need to remove the booster housing to access the captured bearing race & install the bushing.
The "hydraulic system tank" needs to be loosened & tilted back for right rear booster bolt access so:
A) Remove hyd. tube from back of booster (tube to tank).
B) Remove two top tank bolts, loosen bottom two bolts & tilt tank back.
C) Remove all six 17mm booster bolts & wiggle booster housing up off steering mechanism pipe. Mine had never been apart & the two booster housing dowels were tightly fitted so some poly-hammer persuation may be necessary;

5) REPAIR DAMAGE:
If your shaft and/or housing bearing races are gouged up you can quickly fill & fair w/ JB Weld or thick CA glue & catalyst. Clean shaft & abrade damaged areas for mechanical adhesion. Apply JB Weld ASAP if you're in a rush as ideally it should cure overnight before fairing. Catalized CA glue cures almost instantly but it's harder to fair than JB Weld (& stinky). I've easily repaired many badly scored hydraulic parts this way incl the main lift cyl on this tractor;

6) CLEAN:
Solvent flush booster housing, steering mechanism pipe & lower bearing. Clean & dry lower bearing with paper towels/rags taped to a yard stick or similar stuck down through pipe and/or compressed air;

7) MAKE HDPE BUSHING:
A) Drill 1.5" (38mm) thick HDPE sheet with a 3" OD holesaw yielding a 72mm OD puck.
*Use a sharp holesaw & clear chips frequently so poly doesn't turn into a molten mess instead of being crisply cut.

B) Drill 35mm center shaft hole in 72mm OD puck with 1-3/8" (35mm) holesaw to fit 35mm OD shaft races. My four tapered shaft gear teeth were worn so I drilled my center shaft hole 2.5mm off center in the poly bushing to take up slack between the shaft teeth & booster piston thus extending the life of the expensive hardened OEM shaft. Using this method I went from over a full steering wheel revolution of steering play to ZERO PLAY.

The offset shaft hole also allows cam action adjustment so one could drill two or more holes in top bushing face to facilitate rotational adjustments.

C) Mill 4mm x 5mm rabbet/step on bottom of HDPE bushing with router or tablesaw etc. leaving 34mm from top of bushing to rabbet & 62mm rabbet OD. One could skip the rabbeting step by cutting the whole bushing to 34mm thick but I wanted all 38mm for max durability.
*The booster housing bearing race is 33 mm deep so I made my bushing 1mm over-thick for deformative self sealing. FWIW, the black rtv I used in the next step was probably overkill;

8) INSTALL HDPE BUSHING:
Measure​ & mark centerline of widest part of bushing, optionally apply black rtv to HDPE bushing & booster housing race & install with mark on bushing away from booster piston. Spread lower rtv squeeze-out onto booster housing mating surface & tighten six 17mm booster housing bolts. Scrape out any rtv squeeze-out from above w/ a flat blade screwdriver or something;

9) FAIR JB WELD/CA GLUE:
Carefully file & sand JB Weld/CA glue fair on shaft races. Use a lathe if you want to but obv the idea is to remove the filler not bearing race metal;

10) INSTALL SHAFT
Position steering arm so shaft will drop in. Grease shaft, slide common 1.25" ID O-ring keeper & O-ring on shaft to about 2" from the top of the upper shaft race, install shaft (aligning teeth to centered booster piston), install steering arm (pry up while clamping shaft down) & tighten the two 22mm steering arm bolts (tight clearance, use socket & u-joint & flip box & open end wrench. Turn ft wheels with long pry bar for tightening clearance). Top up booster housing oil. If your hyd oil is contaminated with metal filings, drain & flush system & replace oil & filter;

11) GREASE LOWER BEARING AGAIN:
Pump a lot of grease through drain hole (also provides extra leak protection if upper bushing ever leaks). Install drain plug;

12) INSTALL "HOUSING COVER": & adjust "regulator screw;"

13) SMILE: at the time & $ you saved not engineering & buying steering ram parts, replacing the $886 booster/shaft unit or rebuilding the OEM system w/ new $400+ shaft, bearing, housing packing, packing rings etc. ☺️

This quick & cheap fix has stood the test of time with no play or leaks loading a lot of logs big enough to max out the Leon 636 loader.

Happy Trails,
B

« Last Edit: December 28, 2017, 12:16:21 AM by Brought Upright »
  • Belarus 420A