Hi all, I'm after some advice about our d4h lgp direct drive on a 1988. When we had it the gas lever did nothing and we had to jam the pump open from under the hood. I'm after trying to fix it but can work out how the system works? My other question is that is it supposed to have some sort of deceleration pedal on it somewhere as I see no way to drop the revs down to shift forward/reverse. Its a rare machine being a direct drive with so many of them built as powershifts, and as I've seem on so many all of the powershifts have a deceleration pedal fitted. Any help greatfully received.
You don't need a deceleration pedal on a direct drive .
Do you have an Operation Manual.? It sounds as though you could use one.
What's the machine Serial Number.? I'm guessing 2AC or 3AC-something. I can have a shufti at the Parts/Operations Manuals and post some pictures/text.
While looking for a clip explaining the use of a decelerator pedal I found this clip . I wonder if they soaked the welding rods in water when they used them to gouge out the crack for the weld up . I noticed they were called to prayer but skipped it , guessing they will break out the prayer mats between the dozer leaving and being paid . meanwhile the hunt for a decelerator on a direct drive machine continues ......
Thanks for the replies, its a 3ac , it's a friend of mines machine and I've just rebuilt the transmission with a new crown wheel and pinion. The accelerator setup has been jammed on it since he bought it so I'm in the process of making it work properly again. It seems a little harsh when shifting between fwd/reverse and I suggested it may be because its running at high idle when making the shift. The accelerator linkage setup is wildly complicated for something that needs to just rev up and down and screamed to me that something must be missing. But maybe not...
Despite what epirbalex wrote, there is a decelerator pedal on the D4H direct drive and a good operator will use it. It's situated in the same place as it is on the powershift version (8PB) to the right of the service brake pedal. If it's not working correctly (depress to decelerate the engine from whatever rpm the governor lever is set to), then check the linkage from the pedal through to the governor control. I have seen (on other machines) the linkage being reinstalled incorrectly preventing correct operation. The governor control will open up a quadrant plate and the decelerator will pull the quadrant back down against a spring. Until it's working again correctly, just throttle down with the governor control if you want to. You can just declutch with the governor open but you really only want to do that in the lower speeds (e.g. 1,2, and 3. I'd throttle down for 4,5, and 6)
Look for 8g3913 it is the decelerator pedal and linkage it is the same as the one off a 8pb powershift it was a attachment on direct drive
It makes sense to have a decelerator with any transmission. It's a lot easier on the drivetrain when changing direction and faster than moving the hand throttle while shifting between forward and reverse.
Personally I always use the decelerator, takes almost no effort/time and just seems a lot nicer on machine.
My track loader has a twist grip throttle on the gear shift rather than a decelerator pedal. I've read some people don't like it but it becomes second nature to throttle down for a second or two when changing direction.
Direct drives were used for years out here in the Palouse country wheat farms. The machines were run like the track loaders with no decelerator pedals. Cat has always stated that their modulated shift transmissions will work fine without decelerating the engine between direction changes. I don't like it but have had conversations with Caterpillar engineers several times in the past about the issue who said it isn't a problem.
My manual says the trans. is designed for full speed direction changes but decelerating will prolong trans. life. My former neighbor had a 955 and said to just run it at 3/4 throttle all the time.
Well gents, the DD TXM in the H model forward are not same as breed as previous models... Clutch is double disk and wet. They have power reverser, and a modulator pedal. (clutch) I can´t provide , but an operation manual is needed for this, system is much more complex than we tend to imagine. As of me, if i had a DD instead of PS would be great for my job aplicartion, and the decelerator is a must, expecially for slow speed manouvering.