Maybe someone could tell why the newer Caterpillar models do not have locking differentials? I don't spend much time on them anymore; but I sure liked having the traction. I am not sure when Cat started this, but now they are no better than a John Deere. Maybe it is liability... but I think they should at least give you the option. www.terrasmooth.com
I didn't know that the older ones had locking diff's. Exactly which loader were you operating?
The 966 H and 950 K When you get on uneven terrain only one front and one rear wheel will spin... effectively making it a two wheel drive. I know the older models would spin them all regardless of the terrain.
Locking diffs are only a good idea IMHO in soft boggy ground. Put them on hard dry ground and they'll take the tread off the rear tyres in a heartbeat.
I would say that would be true if you were spinning the tires all the time...or on a street vehicle, with someone who did not know how to drive going around corners. I never saw the rear tires wearing out on all of the older model loaders that had lockers.
Cat like everyone else has limited slip differentials as an option. I think I've looked at a couple of Deere loaders that had a button on the console that looked like it might be a locking diff up front but since i didn't spend any time on the machine I'm not sure what it was. I've never actually seen a Komatsu with a locking or limited slip diff but have seen Hough loaders with the limited slip option.
Correct - locking diffs are still an option on most Cat models. Going back to the issue of tyres I had an isue once with a brand-new 992G that the customer complained was tearing up rear tyres, and I mean really mangling them, in a very short space of time. We videoed the machine working and whenever it was moving in reverse and steering you could see the rear tyres hopping. This was on hard dry ground I hasten to add. When I dug into the machine I found it had an (optional) Detroit Locker in the back axle. The customer wanted a machine fast and the salesman found one with another dealer somewhere, however he didn't check the configuration too closely, maybe he didn't even know. Anyhoo, we pulled the rear axle and brought it into the shop where we rebuilt the rear diff as a conventional differential. Problem solved ............. the salesman asked if there was any chance the factory would pay for the conversion - at which point we laughed him out of the office.
You gotta love the sales department. I've seen the same thing at the dealership I work at. The only machine I know of that seems to have a diff lock factory is a garbage compactor. Most of the loaders I've been around were open diff because they spent more time on hard ground than in something soft.
Granted they are compact wheel loaders, but I am fond of the selectable lockers on the Gehl 340/540. A limited slip would be a distant second in my mind. Going from open to locked with the push of a (momentary) button seems ideal until traction control becomes an option.
Nige, All I know is that every Cat loader from a "B" model through "F" would spin all the tires the same... having said that most of my work has been out on the grade and not in a pit. The 992G model was prone to be quirky in my opinion, the single boom wore pins out way faster than a two arm setup and the lift hydraulics were overly sensitive when you lowered the boom... maybe just the weight; it was the only 992 I have ever been on.
I've not run the larger loaders that you seem to be refering to, but in the 3yd class I have run many 930s and 928s. All with limitted slip diffs. I currently own a 544J and it has a locker button (on the floor). I still prefer the limited slip design. Yes the locker button will lock them all together but you are not supposed to use it unless you are going straight. You can feel it bind if you turn while it's locked, so it's not just one of those "wives tales" either. I shutter to think what noises will come if an employee pushes the button while the wheels are spinning. The 544 will get great traction when locked, and I have adapted to it so I get pretty good traction regardless. I still prefer the limited slip because, over all, it gets better traction in more situations. I never have to think about the button either.
Depends which generation of 992G you're referring to. The first ones were a POS, second gen was much better, and by the time the 3rd gen came around it was pretty much right. Sensitive hydraulics was fixed with more software updates than you could shake a stick at. Now the G has been replaced by the K and a few things have changed, but the major one is replacing the 3508B engine with a C-32. A lot of operators didn't like the way the G engine lugged when it was digging, it felt to some like it was stalling. But actually once you understood how the relationship of how the electronics controlled the engine & powertrain the machine was doing exactly what it was supposed to, and it actually meant more power to the implements at lower RPM than would be the case at higher RPM. I have a video that I will try to post somewhere showing the 992G with the locking rear diff literally hopping the rear tyres whenever it was moving in reverse and being steered at the same time. In a straight line it did not do it. The ground at the mine where it was working was as dry as a bone and hard also. I'll also see if I can dig up some photos of the rear tyres that came off it.
The 992 G I was on was around 2001 or 02... must have been a 1st gen. I would think that Cat would have diff lock like they do on their motorgraders, they are definitly positive when engaged, I would never articulate much with it on, you would really notice it putting a bind on the hydraulics.
Nige what you refer to almost sounds like an electronic version of the VCTC that was offered in I believe the 988B and maybe one other model. This was right around the time of the beadless tires. Now Im dating myself.LoL
I know what you mean about being dated. I remember VCTC as well. There are actually 2 systems. One the operator controls, it's effectively an electronic version on VCTC and controls the slip of the converter impeller clutch. The second he has no control over. I think the following diagrams will explain it. The thing is that when the loader is in the pile it does not need the full power of the engine to force it in to the material, you "persuade" the bucket into the material using the hydraulics. So by reducing engine RPM the converter can only absorb a certain amount of the torque produced by the engine leaving the rest available to run the machine hydraulic systems. This diagram is for a 988, the 992 is the same only the RPM on the bottom line will change due to the different engine.
Well must be the one's you ran had all been spec'd with the locking or limited slip diff's. I have worked on many 966's from "A's" to "D's" and only a couple of them had anything other than "open" diff's. Out of dozens I worked on over the years I never saw one that had selectable locking like the 710 John we have has. I did work on a, I believe it was an old 613 self loading scraper that you could lock in as needed. I remember that one as the shift fork had come loose and I had to fix it one day.