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Transmission interupt issue

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3.1K views 25 replies 3 participants last post by  60DRB  
#1 ·
1996 Model# 42910X92A Murray 42" riding mower w/B&S engine.
Hydro-static transmission.
While working on a couple other issues, I used the transmission interrupt/push device so I could push the mower around while working on it. The pin/rod that pushes in so you can move the mower when not under power is stuck in. I sprayed the pin with lots of penetrating oil and tapped on the case with a hammer handle from several angles. The pin won't come back out.
Am I going to have to pull and open the transmission?
 
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#3 ·
Yes. This happened a year or so ago and I told myself to never use the interrupt again once I finally got the pin/rod to come out....
But forgot what I told myself. Ugh.
 
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#4 ·
I do have the mower at MY house now.
...That pin/rod is still inside the case where I can't get any purchase for pliers, etc. to pull it out.
Just cranked the engine and tried forward/ reverse several times each. I presume there's a spring inside that should push the rod out normally.
If I have to open the case, I may as well order a rebuild kit.

How many different hydro-static transmissions (manufacturers) are there for these smaller yard tractor/mowers? Are they the same among different brands, like the engines? Wondering about scavenging from some other brand "dead" mowers...
 
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#6 · (Edited)
I don't have a "strong" magnet...

Mower manual parts diagram does not ID the type trans-axle/transmission. I think it's made by Dana, but how do I find out which model# it is?
Perhaps #4900-3?
 
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#7 ·
I would jack up the rear tire (rear end of tractor) so as both rear tires are off the ground, block the front tires on both sides so as no chance of it taking off, install safety stands under the rear and try rotating the rear tires back and forth by hand while it's in neutral position on shifter and try operating the interrupt lever.

If that don't work try starting the engine while it's jacked up and move the Hydrostat lever forward and reverse several times then back to neutral and try the interrupt.


Might have to search on-line for Dana. Tecumseh peerless had a ID tag or model stamped into the big lower part of the case.

You can download a FREE Tecumseh/Peerless xmission manual on-line and look at it so as to see if it's a Peerless.

Or go to the previous link I sent you and ask them.

I tried to find a free owners manual for your rig but no luck. That xmission pin is called a bypass.
Did you try starting the engine and operating the F/R lever and let it run with the wheels off the ground. It kinda appears that the Hydralic pump pressure is required to automatically push the bypass pin out. (if you cannot do it manually)
 
#8 ·
I already took off the interrupt lever piece that pushes the pin into the case. Tried a mini-magnet hoping to draw the rod out. It's actually indented a bit inside the case. Thought about trying "super glue" on a rod to the end of the interrupt rod and trying to pull it out. Might still.try that, but figure it may well super-glue the stupid rod into the case... But as I will most likely be opening it anyway...
I would love to hear any suggestions, other than what I'm blathering about...
Fiddled with belts, pulleys, brake parts, etc., etc., etc.
I'm fairly certain it is a Dana-Spicer unit.
I've pulled hydro transmissions to change fluid in the past, but I really don't enjoy the grunt work any more (I'm 61). I think that's what I'm going to have to do though, if I want to get this thing running again. It's my BIL's spare mower, so at least I'm not in a big rush.
 
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#11 ·
Doubtful, unless you see where oil has been coming out somewhere, like around a axle.

Can you post up couple picture of what normally pushes down on the interrupt pin?
(reason I ask is on the ones I've seen a lever pushes the pin down to realese the pump pressure and then moves up enough that the pin pushes itself back out to en-gauge the hydralics)

Have you tried using a penetrating oil then hit it with a blast of air pressure so as to clean out a grit then trying gently pushing down on the pin to see if it will go further in just the least little bit so as to free up a slight grit or rust ring)

You may have to just flog into it and get it out so as you can see it better and maybe then see some ID numbers and look at the top of the pin if it's flush with the top of the housing. I would suspect that the pin itself is probably rusty and not sliding freely by spring pressure. If you had the Transaxle out you might be able to gently warm the housing around the pin while doing the penetrating oil. (aluminum expands faster than steel so it might free it up by a slight expansion. I would not peck on the aluminum by the pin with any force or you might make the pin more secure if the aluminum is upset.
Good to hear that someone besides me gets into something that should be minor and have to pull a xmission or engine to correct the problem.
 
#13 ·
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The view is of the left side;
1-is showing interrupt lever as installed, (spring intentionally removed from hole).
2- is closer view of "V" bend that pushes interrupt pin into case.
3- is the hole where the pin is well indented into the case now (with pin push bar removed).
4- just shows where the lever is that operates the interrupt normally (connects to the spring and pin push bar).
 
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#15 · (Edited)
Took the unit out and apart yesterday. It's actually two parts, the axle assembly and the pump assembly. The pump is attached to the axle with two torx screws. Anyway, I opened the top of the pump and looked at it, all looked OK. Re-sealed and closed that. Opened the lower part and that's where I needed to be.
The interrupt pin was all the way inside the case just laying there. There is a plastic part the pin is intended to interact with. That plastic part is/was damaged. I made a partial repair to the plastic part using JB weld. It seems this pump/axle is the most rare item on the planet, as I find absolutely no information on-line as far as schematic or parts diagrams. For sure no you-tube help.
My only question now is, how exactly was the pin to plastic part supposed to interact? What did the plastic part do?

I will not be trying to get the interrupt feature to work, but need to know what position the plastic piece goes in. It sits on the bottom of the case and is held in place by spring tension. Two vertical points/prongs on the piece look like they should be oriented below two holes in the metal. ....maybe? maybe not?

The plastic part "open V" shaped end had little hook catches that were the contact point with the interrupt pin. The interrupt pin would have pushed the plastic piece inward, but to what purpose? If I don't need/want the interrupt feature, does the plastic part even need to be installed? I don't know.
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#16 ·
I do not know the answer to your question, but I test them Hydrostatic type's out of the tractor by spinning the input shaft with a 1/2 inch variable speed drill. When in forward the two axles spin in opposite directions and if you lock one axle the other keeps going with a torque.
Going to reverse the axles spin in opposite direction. This let you get an idea if it might work ok after it's back under the tractor.

Did you ever see any ID info like a model number on the transaxle housing?
 
#17 ·
I do have positive ID on the manufacturer. Dana-Spicer 4900-3.
I will definitely do the "drill drive" test before installation.
 
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#19 ·
Yes I found that stuff, but thank you.
The pump element is is just one piece on the parts list and nowhere can I find that item "exploded".
The entire axle is shown very well. The pump is a *** stepchild it seems.
 
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#20 ·
Yep, appears the 5376 pump is to be replaced as a complete assembly not separate individual parts available and might be NLA or discontinued item and probably kinda expensive when new.

That unit appears to have been used in quite a few Murray/MTD mowers, you might have to do eventually do some lawn mower salvage searching, but keep a heads up because some of those use different wheel/rim fittament onto the axles. I have couple of similar to yours, one has axles like yours, rim keyed and the other has a 4 bolt pattern on a outer hub.

Can you figure out how to get the spring loaded plunger back in for drive?
Wonder if someone pushed the plunger into the housing too Far or with too much force AFTER it would not spring load re-set itself when on the mower?? MAYBE, just a thought.

On the similar Peerless units I just pack the outer axles housing real good with EP2 grease so as the bearing/bushing/seals have a good lube. I do not use the expensive heavy grease that cakes up, it's made from shale and not a good lube after awhile. Them assemblies cannot use oil because it would leak out the outer axles due to not oil seals. If the outer axles have good seals I add little bit a 90-140 oil with the grease. Several of them Peerless transaxles purposely made to wear out, especially the outer bushings in the axle housings.
 
#22 ·
Can you figure out how to get the spring loaded plunger back in for drive?
-If you mean the pin than pushed in to interrupt normal operation, it's glued in place with gray gasket maker...never to be pushed in again.

Wonder if someone pushed the plunger into the housing too Far or with too much force AFTER it would not spring load re-set itself when on the mower?? MAYBE, just a thought.
- Um, that would have probably been ME (this time). It had been stuck in a couple years ago and after finally getting it to come out I told BIL to never use the interrupt again.... Then I forgot all about it when replacing all four tires, the carburetor, battery, etc.

I'll take/post pictures of the parts as they are normally installed later today. The more I look at the plastic part, the more I wonder if it could just be left out???
 
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#23 ·
All back together, with the plastic part points under the holes... don't know if that has any functionality at all. Just looked right. The spring rests in a pocket in the plastic part, and just pushes up against the casing above it...no seat or anything. Odd.
Second picture shows pin/interrupt button sealed from inside. The last three pictures show the interface between pump and axle unit.

I did a test just spinning the input shaft and all seems to work, forward and reverse. It took 20 oz. of Mobil-1 10-40 synthetic (what I had handy).
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#24 ·
All back together and running/mowing like....a 25 year old mower.:LOL:
Just have to tweak the new carburetor a little. Pops and backfires at low rpm.
 
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#25 ·
Great about your xmission.
Did you get the little plunger to spring load or are you just winging it with full time travel?

What engine is that Briggs?

Single cyc L head, OHV or Twin?

One reason I ask is if tweaking don't work I can quite often drain the gas out of the carb bowl and get a good idle and run without having to remove the carb. Seems they get little bit of maybe water in the bottom of the bowl and it won't go away until it's drained.
(
 
#26 ·
Single, OHV. Carb can stay on, just screw adjustments I think. It just went from box/new straight on.
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