MF 135 differential lock engaging

[Norwegian]

Hi!

I have read through the posts I could find about the differential lock on the Massey Ferguson 135, but I ask anyway:

I'm able to turn the shaft 1/2" , but then the pedal slips and the shaft won't move any longer. I don't hear any grinding or anything when I do this.

How much force do I need on the pedal to engage the differential?

What's the distance between the pedal and the floor when the differential is not engaged?

 

[shona13]

G'Day Norwegian.
The 135 and 148 tractors were bad for this ,the bolt that Pinches or locks the pedal to the shaft should be as tight as you can get it without snapping the bolt,or you could replace the original bolt with a Grade Eight High tensile bolt and nut Caterpillar use these type of bolts this will make sure the pedal will grip the shaft nice and tight Before tightening the bolt pull the pedal up say 150mm from the footplate then tighten the bolt .
When you want to engage the differential lock put light pressure on the pedal say a little bit more than the weight of your leg and as you drive along the pedal will engage the differential.consider that the differential and the differential lock each have say a castellated type shape and they both have to line up before they engage which sometimes can take say 10 metres of travel ,it will help if you drive along holding the pedal down and turn left or right a plittle bit this will help engage the differential.
You will also find that it sometimes takes a long time to disengage this is because there is a torque load on the differential lock the best way to release it is again turn the steering slowly left and right say travel 5 metres slightly to the left then 5 metres to the right you will find the pedal clicks up on it's own Make sure the pedal return spring is connected this helps pull the pedal up.
Regards.
Hutch.:thumbsup:

 

[PatrickS2222]

The diff lock will engage only if the slots in both halves of its coupling are lined up. One is splined to the RH axle, the other I believe is on the side of the diff carrier. When engaged, it locks the RH axle to the diff, which makes both axles drive at the same speed and they cannot turn independently of each other.

It is important to know to never push the diff lock pedal when one rear wheel has lost grip and is turning much more quickly compared to the other. Also, driving on sealed roads or concrete will result in very difficult steering. These practices will certainly damage or break components.

Lift the pedal and tighten collar bolt to ensure full travel, drive the tractor slowly whilst steering a little to one side. At the same time, gently push the diff lock pedal and you will feel when it engages. It will lift only when there is no side load on the diff lock, so steering a little the other way, or reversing, will allow it to release. Stop the tractor as soon as it releases, select neutral and apply the parking brake. Push the diff lock pedal again - it should readily engage and release if the tractor has not moved. The process may need to be repeated a couple times to achieve this. You can then set the pedal height and lock the collar bolt. The pedal should be set at 6-12mm (1/4-1/2") from the footrest when fully engaged. :thumbsup:

Ours has had a seized shaft for years. I gently brush one steering brake if grip is poor on one wheel. I find this does not steer me in a direction I don't want to travel when I'm pulling something heavy.

Hope this is helpful.

 

[Norwegian]

G'Day Norwegian.
The 135 and 148 tractors were bad for this ,the bolt that Pinches or locks the pedal to the shaft should be as tight as you can get it without snapping the bolt,or you could replace the original bolt with a Grade Eight High tensile bolt and nut Caterpillar use these type of bolts this will make sure the pedal will grip the shaft nice and tight Before tightening the bolt pull the pedal up say 150mm from the footplate then tighten the bolt .
When you want to engage the differential lock put light pressure on the pedal say a little bit more than the weight of your leg and as you drive along the pedal will engage the differential.consider that the differential and the differential lock each have say a castellated type shape and they both have to line up before they engage which sometimes can take say 10 metres of travel ,it will help if you drive along holding the pedal down and turn left or right a plittle bit this will help engage the differential.
You will also find that it sometimes takes a long time to disengage this is because there is a torque load on the differential lock the best way to release it is again turn the steering slowly left and right say travel 5 metres slightly to the left then 5 metres to the right you will find the pedal clicks up on it's own Make sure the pedal return spring is connected this helps pull the pedal up.
Regards.
Hutch.:thumbsup:

G'Day Hutch, thanks for the well written explanation :thumbsup:

I was thinking about drilling a small guiding hole in the shaft for the bolt to lock in to, to keep the pedal from spinning.

The vehicles I've driven have had a button for engaging and disengaging the diff. lock, quite different from this old timer

We have winter her now with around -7°C and snow on the roads. I was trying to pull a trailer full of fire wood, but even with snow chains it started spinning on one wheel so I had to give up But I'll have a look at it during the weekend.

 

[Norwegian]

The diff lock will engage only if the slots in both halves of its coupling are lined up. One is splined to the RH axle, the other I believe is on the side of the diff carrier. When engaged, it locks the RH axle to the diff, which makes both axles drive at the same speed and they cannot turn independently of each other.

It is important to know to never push the diff lock pedal when one rear wheel has lost grip and is turning much more quickly compared to the other. Also, driving on sealed roads or concrete will result in very difficult steering. These practices will certainly damage or break components.

Lift the pedal and tighten collar bolt to ensure full travel, drive the tractor slowly whilst steering a little to one side. At the same time, gently push the diff lock pedal and you will feel when it engages. It will lift only when there is no side load on the diff lock, so steering a little the other way, or reversing, will allow it to release. Stop the tractor as soon as it releases, select neutral and apply the parking brake. Push the diff lock pedal again - it should readily engage and release if the tractor has not moved. The process may need to be repeated a couple times to achieve this. You can then set the pedal height and lock the collar bolt. The pedal should be set at 6-12mm (1/4-1/2") from the footrest when fully engaged. :thumbsup:

Ours has had a seized shaft for years. I gently brush one steering brake if grip is poor on one wheel. I find this does not steer me in a direction I don't want to travel when I'm pulling something heavy.

Hope this is helpful.

Thanks for the advice, Patrick, highly appreciated :thumbsup:
Especially splitting the brake pedal and brake on the spinning wheel was a clever idea! Too bad the "pin" that locks the pedals together is rusted stuck :laughing:

I have driven cars, tractors and semi's with diff. lock so I understand the concept, but they've all had an electronic button for it :laughing:

 

[shona13]

G'day Norwegian.
the shaft is very hard I don't think you will be able to drill it.
What is Snow!
Regards.
Hutch.

 

[PatrickS2222]

G'day Norwegian.
the shaft is very hard I don't think you will be able to drill it.
What is Snow!
Regards.
Hutch.

G'Day Mate, Snow is nature's way of telling you it has become much too cold! :shocked:
Either build a huge fire and stay near it, or move to coastal Queensland, Northern Territory or northern Western Australia ... but be sure to stay near the coast! :thumbsup: PS: Fishing's good too :licking:

Norwegian, spray it with anti-seizing fluid over several days and it should move - just be patient. I don't think it is cast iron, but it might bend with too much force, so a bit of patience is great. Once it loosens up, some spray-grease once in a while will keep it usable.

If all else fails:
S.42597 Brake Pedal Lock Latch.

In such a harsh climate, a squirt on the diff lock shaft will help it too, also brake linkage joints and shafts, 3PL lift linkage pins ... the list is almost endless. You will find it is an asset to have an option to separate the brake pedals ... mine stay that way, I habitually and automatically just put my boot on both (or deliberately on just a particular one) without looking.

The types of diff lock control you have previously used might have been applied by compressed air and released by a strong spring.

Just be aware to "brush" or brake gently and progressively the slipping wheel - as with any situation where the level of grip is close to being exceeded - "slowly + carefully + gently = safely".

 

[shona13]

G'day PatrickS2222.
The foot brake lock bar! Indeed a very handy thing when you want to turn in tight places used carefully of course.
The problem with the lock bar is that the bolt has a shoulder and it and it is a tight fit on the pedal this is why they seize so easily , to remove loosen the nut ,spray and heat ,gently work the head of the bolt from the bottom and when you get it apart drill or file the hole on the brake pedal or file the shaft of the fitted bolt a little bit then you can oil it now and then, It will be tight but with care it will come out.

Talking about the Diff lock ,The pedal assembly is made of High carbon cast Steel and would take some breaking, where the diff lock shaft locates in the Trumpet /bell housing there is a very thin brass bush this quite often becomes so worn that it will seize to the shaft and it will turn in the housing ,no real problem as said keep spraying with crc or whatever I did have an occassion when I had to heat the pedal area around the clamping part and tighten it up when the casting was still hot.

Snow.
I know what Snow is having been brought up on my uncles dairy farm back in Scotland ,Driving tractors in the freezing cold,rain, snow, no cab yuk that is one of the reasons I migrated to Western Australia in the seventies, Still the best place in the world to live in.
Regards.
Hutch.

 

[Norwegian]

Thanks for all the feedback!

I just had a test drive and the lock seems to engage now :thumbsup:
However, the pedal will not stay down for more than a few seconds, but I assume that is because I had good traction and no spinning. With some force/load I assume the differential will stay locked and the pedal will stay down. Will try tomorrow when I go in the woods with it.

Here is what it looks like today:

 

[shona13]

G'day Norwegian .
You can have the cold weather!!.
When using the diff lock you have to keep your foot on the pedal all the time it is in use, as soon as you take your foot of the pedal and the torque load is lost the pedal will spring up /out of engagement this is how it works,not like a truck where it is held engaged with air or whatever.
Hutch.