840 payloader brakes
Printed From: Unofficial Allis
Category: Allis Chalmers
Forum Name: Construction and other equipment
Forum Description: everything else with orange (or yellow) paint
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=144739
Printed Date: 10 Jan 2025 at 6:20am
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com
Topic: 840 payloader brakes
Posted By: giffenfarms
Subject: 840 payloader brakes
Date Posted: 23 Nov 2017 at 9:15pm
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Hey guys, we have an 840 payloader with no brakes, this is our 3rd loader, with the same brake issues as the last 2 had. What are people doing for brakes and where to find parts, we fixed the brakes last winter but are back to where we were, these aren't that popular of a loader around here and not too many people know how to work on them. Any help in any direction would be appreciated. Cheers, |
Replies:
Posted By: Coke-in-MN
Date Posted: 24 Nov 2017 at 10:34am
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Sounds like they are vacuum over hydraulic operation so the first thing to look at is vacuum booster in the system . Might look at changing it over the hydraulic booster like used on some diesel pickups has a old Pettybone 2 yard loader and chased brake problems on that - booster was the problem each time - it used a small vacuum pump that was belt driven and a small tank to help if and when you lost engine power to pump . Doing a search it seems 840 chatter is on the vacuum booster being at center of problems and finding a working unit is hard ------------- Faith isn't a jump in the dark. It is a walk in the light. Faith is not guessing; it is knowing something. "Challenges are what make life interesting; overcoming them is what makes life meaningful." |
Posted By: Brad in WA
Date Posted: 25 Nov 2017 at 12:40am
| 840's have a hydraulic booster, it gets oil from the power steering pump. I put a disc brake on mine, machined a plate and mounted it just ahead of the parking brake. Used a Chevy pickup caliper. Works great. |
Posted By: giffenfarms
Date Posted: 21 Dec 2017 at 5:31pm
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Pulled everything apart, everything is in working order, puzzled, shoes are ok for being original, brake cylinder and booster both work |
Posted By: DMiller
Date Posted: 21 Dec 2017 at 5:36pm
| Air in system? |
Posted By: giffenfarms
Date Posted: 21 Dec 2017 at 6:36pm
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Posted By: giffenfarms
Date Posted: 21 Dec 2017 at 6:45pm
She's getting a complete check over, next on the list once we figure out the brake problem is to replace the center pivot pins, lots of movement 
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Posted By: JohnCO
Date Posted: 21 Dec 2017 at 9:13pm
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What a beautiful shop you have! Sorry about that red tractor with the hood up...lol ------------- "If at first you don't succeed, get a bigger hammer" Allis Express participant |
Posted By: Coke-in-MN
Date Posted: 21 Dec 2017 at 10:05pm
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Might look at using a hydraulic booster and master cylinder from a Chev Diesel pickup as they used power steering pump pressure - many machines use a accumulator to store hyd pressure to allow brakes to work if engine kills . So could be you hyd pressure or the fact the booster isnt working ------------- Faith isn't a jump in the dark. It is a walk in the light. Faith is not guessing; it is knowing something. "Challenges are what make life interesting; overcoming them is what makes life meaningful." |
Posted By: jerbob
Date Posted: 22 Dec 2017 at 11:02am
| Can only see the floor and the lighting but that looks like a great shop. |
Posted By: Adam Stratton
Date Posted: 30 Dec 2017 at 8:50am
| I am impressed too! Can you give me some insight into what has to happen to pull the drums on that machine? I have an 840 that has leaking cylinders on the wheels. Does the drum come off simply after removing the wheel or do you have to take the big "hub" off too? Thanks in advance! |
Posted By: giffenfarms
Date Posted: 30 Dec 2017 at 12:08pm
There is a booster on the pump, everything works when we pulled the drums off, which is the confusing part. |
Coke-in-MN wrote:Posted By: giffenfarms
Date Posted: 30 Dec 2017 at 12:22pm
I'm doing a complete service on it and to check the cylinders and shoes, the drums come off by removing the 10 of 12 bolts on the hub, the pull out axle, there is a big nut that has to be removed with hammer/chisel, pull the bearing then the drum should come off, it's pretty straight forward. We're have the rear axle shoes sent away to be re-shoed, pop the rivers out and put new pads on. |
Posted By: DMiller
Date Posted: 30 Dec 2017 at 1:01pm
| Probably should check to see the booster is actually making 'Boost'. Could be internally gummed up or trashed out. |