Sunday, January 22, 2012

Downshifting in a 793

Lots of people send it photos to this blog. (Thank you!). Normally,  I check them to see if I already have them in my collection, and then put them into the rotation. Sometimes, the photos are so amazing that I just have to put them up on the site right away.

This is one of those times. These photos were sent in this week by a reader. In it, he says that the operator of this 793 downshifted from sixth gear to first. The engine didn't like it. Some rebuilding of the engine may be necessary.












13 comments:

Anonymous said...

That is awesome. I'm glad I wasn't in the engine bay at the time, it looks like an anti-tank mine went off in there.

Anonymous said...

The story's a load of BS. The tranny won't downshift from 6th to 1st like that.

Anonymous said...

Looks like the floor of a slaughter house!

Anonymous said...

Ref the comment above. Not necessarily total BS. There WAS an electronic issue where transmissions would experience a 5th or 6th speed to 1st speed downshift around the 1999-2000 frame. However although I personally saw a few engines that had this problem none of them ever grenaded like this one, the worst that happened was a single connecting rod through the side of the block.

See here if you want more discussion on the subject.....

http://www.heavyequipmentforums.com/showthread.php?27240-793-with-a-slight-mishap&p=338567#post338567

Anonymous said...

Sunrise dam 793 after a midlife??

There was an engine which let go in similar fashion after a rag (which was left in the sump) blocked the oil pickup

Not sure is these are from the same incident though

Anonymous said...

looks like an oil pan failure to me.....a failure to catch all the broken parts!!

Anonymous said...

The last photo with the guy holding a Pepsi can is a Liebherr Haul truck, not a CAT.

Anonymous said...

Good to see it always comes down to operator error, what a load of crap!

Anonymous said...

Na, we got a safety alert sent direct to our site, in the description it stated the engine did downshift 6th - 1st due to a ECM error, apparently after downloading the VIMS info it showed the engine reved to 4000rpm for a very, very short time..

Anonymous said...

if it did somehow down shift 6th to 1st its definitely an electrical error and no fault of the operator

James Kermode said...

If you are running down a ramp after the water cart, the transmision will down shift when the wheels stop turning. The truck will still be traveling at full tilt, but the computer doesnt know that, so when the transmision engages 1st, the truck is still moving at 30 0r40 kmh, and when the wheels start to turn again the motor over revs up to more that it was ever designed to. been there and its not a nice sound. Didnt blow the motor, but a shit-load of alarms came on.
Cheers, James

Anonymous said...

Yeah that's why you SLOW DOWN. It's like a race for you dumbasses, get back to the digger as quick as I can so I can read my Picture mag.

Fucking Boneheads.

joe said...

Safe to say that positive torque converter lock up was achieved through out the entire range of RPM from 2000 to ZERO

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