1965 David Brown 990 Backhoe loader lost all drive

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hschwartz3
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Location: Amanda, Ohio USA

Re: 1965 David Brown 990 Backhoe loader lost all drive

Post by hschwartz3 » Sun Jan 08, 2017 7:14 pm

Here are some more pictures


These first few pics I had nuts wedged under the end of the clutch release levers to help get the clutch out of the tractor.

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I can't seem to find anything out of place with the clutch.All of the bearings move freely with the exception of the pilot bearing in the flywheel. i don't think it is even used here because there is no PTO.
1965 David Brown 990 Backhoe Loader
1973 David Brown 990 Selectamatic

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db2d
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Re: 1965 David Brown 990 Backhoe loader lost all drive

Post by db2d » Sun Jan 08, 2017 8:05 pm

Where are the circlips that should be on the clutch driveshaft ?

When the drive failed, was there any resistance other than that from the return spring on the clutch pedal ?

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hschwartz3
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Re: 1965 David Brown 990 Backhoe loader lost all drive

Post by hschwartz3 » Sun Jan 08, 2017 10:39 pm

db2d wrote:Where are the circlips that should be on the clutch driveshaft ?
They were removed by the time of those pictures, there was one under the "oil slinger" in a groove right behind the thrust bearing carrier / support snout, and the other one was up against the muff coupling but was not in its groove.
db2d wrote:When the drive failed, was there any resistance other than that from the return spring on the clutch pedal ?
yes, the clutch pedal felt normal.
1965 David Brown 990 Backhoe Loader
1973 David Brown 990 Selectamatic

SteveCollett
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Re: 1965 David Brown 990 Backhoe loader lost all drive

Post by SteveCollett » Tue Jan 10, 2017 11:05 am

You say it coasted to a halt.
The clutch looks fine to me , but as others say without measuring it you cannot be 100% sure but I would be amazed if that clutch had suddenly given up its ghost. When they do that normally it has sheared the rivets or some such.

So looking at the alternatives.
When it stopped how was the gear lever?
It had not dropped out of the selector, leaving the tractor in neutral?
just a thought

1952CROPMASTER
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Re: 1965 David Brown 990 Backhoe loader lost all drive

Post by 1952CROPMASTER » Wed Jan 11, 2017 1:05 am

I know it's a stupid question!!!!, Have you checked the Crankshaft, i have heard of one braking just behind # 4 connecting rod, just a thought

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hschwartz3
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Re: 1965 David Brown 990 Backhoe loader lost all drive

Post by hschwartz3 » Wed Jan 11, 2017 4:38 am

SteveCollett wrote:You say it coasted to a halt.
The clutch looks fine to me, but as others say without measuring it you cannot be 100% sure but I would be amazed if that clutch had suddenly given up its ghost. When they do that normally it has sheared the rivets or some such.
I think the clutch looks fine to me too. i was stripping ground right before this happened, low rpms, low range, 1st gear, loader bucket down hard, front wheels off the ground, diff lock engaged. rear wheels would spin out once bucket was full. I'd be surprised if the clutch suddenly went out without making a sound.

My only question about the clutch would be....what would happen if the clutch shaft slid backwards towards the transmission? the circlip back by the muff coupling was not in its groove. i could see the clutch shaft was in the clutch disc closest to the trans but could not see the plate next to the flywheel. would it drive with just the one disc?
So looking at the alternatives.
When it stopped how was the gear lever?
It had not dropped out of the selector, leaving the tractor in neutral?
just a thought
This was my initial thought when it coasted to a stop. When backing up, I turn in my seat a bit to look behind me. I thought maybe my knee bumped the transfer case (high/low range) into neutral. This is what it was acting like. i shut the tractor off, I could hear gears sliding back and forth as i tried every selection.

I still could have a problem with the transmission. one of the pictures i posted earlier showed some pretty badly worn high /low range gears. possibly they are worn to the point the gear lever wont engage them. I'm speculating.

the weather hasn't been cooperating with me the past few days, once i get a break, i'm gonna put the tractor back together enough to continue the diagnosis.

again, thank you all for the help.
1965 David Brown 990 Backhoe Loader
1973 David Brown 990 Selectamatic

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hschwartz3
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Re: 1965 David Brown 990 Backhoe loader lost all drive

Post by hschwartz3 » Wed Jan 11, 2017 5:01 am

1952CROPMASTER wrote:I know it's a stupid question!!!!, Have you checked the Crankshaft, i have heard of one braking just behind # 4 connecting rod, just a thought
Not a stupid question. I am aware of the crank problems with these tractors and it did cross my mind. however, I can put a socket on the flywheel and turn the radiator fan. Also, before removing the starter i was able to start the tractor several times. the starter turns the flywheel, which turns the crankshaft. So i feel confident the crankshaft is not broken.

it does bring up another possibility. Crank Walking. I have't checked that yet. Would it even cause my issue?
1965 David Brown 990 Backhoe Loader
1973 David Brown 990 Selectamatic

joeproctor
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Re: 1965 David Brown 990 Backhoe loader lost all drive

Post by joeproctor » Wed Jan 11, 2017 7:32 am

cranks dont break like they have been 'parted off' in the lathe they shear and make a lot of noise,like big ends but magnified,
the clutch is a twin plate single acting like a lot of skid units that do not have a pto,i doubt that you could rip the middle out of both clutches at the same time,are you sure you did not knock it out of gear-----it seems a sensible solution------but a time consuming mistake!

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rid54
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Re: 1965 David Brown 990 Backhoe loader lost all drive

Post by rid54 » Wed Jan 11, 2017 2:49 pm

If this were a car (which of course i isn't), I'd be asking questions about differential gears and drive shafts and splined joints... Can you verify that you have soild drive from the wheels to the gearbox input shaft (with any gear engaged)? Block one wheel, turn the other - gearbox input shaft should turn.

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db2d
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Re: 1965 David Brown 990 Backhoe loader lost all drive

Post by db2d » Wed Jan 11, 2017 6:59 pm

Second/fith gear on the layshaft is very badly worn and if the sliding gear on the pinion shaft is in the same state, this is probably the reason for the loss of drive. Engage second gear and check the amount of mesh available.

Gard
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Re: 1965 David Brown 990 Backhoe loader lost all drive

Post by Gard » Thu Jan 12, 2017 3:26 pm

From an earlier post it seems like the transmission is working at least to some extent "turning the Muff shaft rotates the rear wheels"
The clutch plates are intact
I am no expert but I wonder if the problem could be someplace between the clutch pedal and throw out bearing. The actual movement at the clutch is quite small so if something slipped just a little... or a broken key
When you first looked thru the clutch inspection plate did you notice if the plates move when the pedal is depressed? I guess this type of fault would most likely result in a clutch that fails to release than one that fails to drive.

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hschwartz3
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Re: 1965 David Brown 990 Backhoe loader lost all drive

Post by hschwartz3 » Sun Jan 15, 2017 7:09 pm

hi guys,

i finally got a break in the weather to work on this tractor. i was trying to re-install the clutch to see if i can troubleshoot this tractor some more. I've run into a bit of a snag trying to reassemble the clutch. it isn't going together the way it came apart.
i will do my best to explain it with some pictures.

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in this picture, i get the clutch assembly back in the tractor this far, i have wedged some nuts under the outer clutch fingers to aid in the installation. if you look at the pressure plate bolts i don't have that far to go. my problem is... if i tighten up the pressure plate bolts any farther the nuts under outer part of the clutch fingers fall out. see next picture.

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that ain't gonna work and that is not how it came out of the tractor. i can only assume i have a plate in backwards. i have installed this thing twice with the same results.The manual i am using shows a picture with the hub of the first disc (10") pointing towards the flywheel and the hub of the disc for the second plate (11') pointing towards the transmission. then the manual later describes pointing both hubs towards the flywheel. i have tried it both ways with the same results. the first method seems the most logical. i didn't mark them so i already realize that mistake.

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in this picture the pressure plate works like it should. i weigh @200 lbs and it takes my whole body weight to compress the center inside of each finger.

any suggestions would be greatly appreciated.
1965 David Brown 990 Backhoe Loader
1973 David Brown 990 Selectamatic

joeproctor
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Re: 1965 David Brown 990 Backhoe loader lost all drive

Post by joeproctor » Sun Jan 15, 2017 10:38 pm

if you have tightened the cover you may have buckled the plates and this will hinder the plates sliding on the shaft thus not releasing ,it is obvious which way the bosses of each plate go!

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db2d
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Re: 1965 David Brown 990 Backhoe loader lost all drive

Post by db2d » Sun Jan 15, 2017 11:18 pm

The three nuts should fall out when the cover assembly is tightened,there would be a problem if they didn't. Set the gap on the three adjustment screws at 0.050 inches.

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hschwartz3
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Re: 1965 David Brown 990 Backhoe loader lost all drive

Post by hschwartz3 » Mon Jan 16, 2017 1:48 am

joeproctor wrote:it is obvious which way the bosses of each plate go!
There are no manufacturer markings left on these plates, and the manual i have shows one way and describes another. So it isn't obvious.

heres the manual i'm using:
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this is a picture of the newer style twin clutch 10"/10" (similiar but not the same as mine.)
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this is in the section for a dual disc clutch 11"/10" with PTO (similiar but not the same as mine.)
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1965 David Brown 990 Backhoe Loader
1973 David Brown 990 Selectamatic

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