AC 45 Grader Gearbox Information needed

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   The gear selection in these is one
lever for 1, 2 and 3 and a second for High, Low and Reverse.  Ours
has become locked in Ist, so useable so long as 1^st and
4^th will do.
The grader is on the back of the semi
that brought it home which limits any testing for now.  Though a
better working surface than out on the flat.
I wasn't driving when it happened and
there were no new noises heard.  The oil does not contain any
unwelcome shrapnel.
We have copies of the service manual
(which isn't very informative on this area) and spare parts manual. 
Which suggests that the main machinery should not be the cause –
pointing to selectors.
Naturally there is minimal space
between gearbox and chassis.  The selector interlock block is
accessable (moderate pain).  There is space to remove the gearbox
side plate but limited room to see internally past the selectors. 
The area has been visited before (pre-us) as one of the interlock
block bolts is stripped in the gearbox housing and has its nut welded
to the block so it still acts as a hold down for the dust cover.
The interlock plungers didn't stay in
place when I took that area apart but the selector rod came free.  It
remains free now reassembled.  But that rod's half of the square
notch that allows the gear lever to move between planes is off by
about 3'16”.
The shift forks are clamped to the
rails by two bolts so the rail for 2 and 3 could be moved some. I
don't know as yet if both neutral detents are engaged.
But before that experiment – does
anyone know of a service manual that explains the setting up of the
shift forks and<if so,  could I get a “How to” please.
TIA
Ian

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Ian Beale Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Joined: 03 Oct 2011 Location: New South Wales Points: 933	Post Options Post Reply Quote Ian Beale Report Post Thanks(0) Quote Reply Topic: AC 45 Grader Gearbox Information needed Posted: 11 Feb 2024 at 7:39pm
	The gear selection in these is one lever for 1, 2 and 3 and a second for High, Low and Reverse. Ours has become locked in Ist, so useable so long as 1^st and 4^th will do. The grader is on the back of the semi that brought it home which limits any testing for now. Though a better working surface than out on the flat. I wasn't driving when it happened and there were no new noises heard. The oil does not contain any unwelcome shrapnel. We have copies of the service manual (which isn't very informative on this area) and spare parts manual. Which suggests that the main machinery should not be the cause – pointing to selectors. Naturally there is minimal space between gearbox and chassis. The selector interlock block is accessable (moderate pain). There is space to remove the gearbox side plate but limited room to see internally past the selectors. The area has been visited before (pre-us) as one of the interlock block bolts is stripped in the gearbox housing and has its nut welded to the block so it still acts as a hold down for the dust cover. The interlock plungers didn't stay in place when I took that area apart but the selector rod came free. It remains free now reassembled. But that rod's half of the square notch that allows the gear lever to move between planes is off by about 3'16”. The shift forks are clamped to the rails by two bolts so the rail for 2 and 3 could be moved some. I don't know as yet if both neutral detents are engaged. But before that experiment – does anyone know of a service manual that explains the setting up of the shift forks and<if so, could I get a “How to” please. TIA Ian

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DiyDave Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Access Joined: 11 Sep 2009 Location: Gambrills, MD Points: 50528	Post Options Post Reply Quote DiyDave Report Post Thanks(0) Quote Reply Posted: 11 Feb 2024 at 8:12pm
	I don't know whether this is correct or helpful, but I think it's a Clark transmission. No help on a model number, never been into mine...
	Source: Babylon Bee. Sponsored by BRAWNDO, its got what you need!

SteveM C/IL Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Access Joined: 12 Sep 2009 Location: Shelbyville IL Points: 7981	Post Options Post Reply Quote SteveM C/IL Report Post Thanks(0) Quote Reply Posted: 11 Feb 2024 at 11:15pm
	Over 50 yrs ago I replaced a fork twice in an AD40. I think it was same trans. Don't remember squat about it but had no book and made it through. I was 16-17yrs old then. Pretty sure it had interlocking rails. If I could do it back then you can figure it out now. Best I can do.

Pusher Members Profile Send Private Message Find Members Posts Add to Buddy List Bronze Level Joined: 04 Jul 2023 Location: Victoria aus Points: 8	Post Options Post Reply Quote Pusher Report Post Thanks(0) Quote Reply Posted: 22 Feb 2024 at 2:03am
	ian, i have a workshop manual which has section labelled installation of gear shifting forks and shafts. any chance that is what you are looking for cheers Michael L.

Ian Beale Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Joined: 03 Oct 2011 Location: New South Wales Points: 933	Post Options Post Reply Quote Ian Beale Report Post Thanks(1) Quote Reply Posted: 23 Feb 2024 at 4:40pm
	Pusher Thanks for the reply. I think I have that manual. There isn't a lot of room to see what is going on when in the grader. Any way an update so far - After pondering that manual and the parts book I punted that it was unlikely that the lock up was due to anything in the cog works. Helped by not draining anything significant out with the oil. So, if in the selectors, it could have had to do with the interlocks. And when I took that section apart it did - but they didn't stay in place so I could see "How it did". There didn't seem to be noticable wear on any of the plungers to help hang the shift rail. So it went back together and there are 3 in 4 chances that the plungers are not in the same position. But then the square at the front that allows shift lever movement across shift planes was only about half lined up so you had to brute force at an angle to get to 2 and 3. So (punting again) I got a measurement on where the 2 / 3 shift fork was and released the clamp bolts on that fork. The fork stayed stationary and the shift rod moved to match the square. So we now have shift lever movement that suggests we ought to have all three gears. The grader is still on the trailer that brought it home and there is a reluctance to try live gear selection before it is unloaded. The ramp for that is under construction so I'll report later. The grader has been in use for 10 - 12 years so why this happened is a good question. All the shift fork clamp bolts were tight so there shouldn't have been movement there. When we got it it kept falling out of 2nd. I eventually worked out that, due to wear in the selector fork and the way it was positioned that 2nd was only engaging the long teeth of the dog clutch before the shift lever hit the frame front member. I rejigged so it fully engaged and it has worked till now. More evidence of prior selection problems of some sort - the interlock block is held on with 4 long bolts. Nuts threaded on the front hold the block and the other end holds the dust cover. One is stripped in the gearbox housing and the nut is welded to the interlock block so it still helps hold the dust cover. More when I know more. Edited by Ian Beale - 23 Feb 2024 at 8:36pm