On a TV show recently, I saw a clip of a new body style mog, i think it was a U500. The Benz representative explained all about the truck, including something about three 'transmission' type devices, one of which seemed to have an integrated transfer case with a forward and reverse selector. There were like 8-10 forward gears and aboutt the same in reverese and then some other gears were forward only, i think.

I know that mogs dont have a standard manual trans with a t-case bolted to the rear, like most people are used to seeing, but he was quoting something like 4000:1 crawl ratio or one inch per hour or something crazy like that.. I know a bit about mogs, the portal axles, etc and have actually piloted a 1250 series mog when Eurotruck had their original facility, It was damn cool even if it was only around the block..

I'm certain that someone here can explain this in simple terms.

Thanks

Whats your question?

My 416 with cascade box is down in the neighborhood of 4000:1 in first gear super-crawler so I'm sure the new-fangled U500 gearing is somewhat like that.

Yeah - you can easily walk faster then the bottom 4 or 5 speeds. Super crawler is pretty near worthless unless you're attacking a snow face with a cutter, laying in cable or something like that. I never put my truck in super-crawler - matter of fact, I have it 'locked out' with a bolt across the gate...

Sorry if i wasnt clear on the question, how does a transmission and transfer case (or multiples of each) combine together, mount, shift, etc, to give you over 4000 to 1 crawl ratio? It seems a crawler box may mount to the bottom of the transmission? I remember there were quite a few levers for shifting in the large Mog that I drove.

If axles are 7.56 and 1st gear is 7.56, you would need 75:1 in the transfer case or cases to reach those numbers..

If axles were 7.56 and first gear were 15:1, you would still need over 30:1 in the transfer case or a second transmission of some kind.

The new mog engine puts out 250hp and more than double that in torque, not a huge power house, but at 4000: 1 crawl ratio, the torque at the wheels (even for snowblowing or vibratory trenching) is over 2 MILLION pound feet of torque

Thanks

http://www.rockymountainmoggers.com/gears.html

http://www.rockymountainmoggers.com/gears.html

..and that chart only gives normal and crawler gear ratios - not super-crawler (that chart is actually for a 404).

In 1st gear super-crawler the 416/406 UG2/27 transmission gear ratio is 623.05:1 - figure in the diff/portal gear ratio and.....

(that chart is actually for a 404)

Yeah I know, its all I could come up with really quick.

The chart shows the 404 and 3 different 406/416 differentials.

But you're right it doesn't show the super-crawlers.

This reminds me of a guy that came to NWMF this year in a Jeep and was saying that one of his buddies just got done bolting 3 t-cases together and was aiming to get over 1000:1. He asked what a Unimog has and someone shouted out 4000:1 and the guy pretty much crapped and called his buddy up on the phone.... hehe

Stuff like this amazes me about the Unimog that you can get a decent 404 with portal axles, the gear ratio and it runs for around $6000. I don't know how much people sink into their other rigs but I wish I would of found the Unimogs earlier before dumping thousands and thousands into other rigs.

Yeah I know, its all I could come up with really quick.

The chart shows the 404 and 3 different 406/416 differentials.

But you're right it doesn't show the super-crawlers.

This reminds me of a guy that came to NWMF this year in a Jeep and was saying that one of his buddies just got done bolting 3 t-cases together and was aiming to get over 1000:1. He asked what a Unimog has and someone shouted out 4000:1 and the guy pretty much crapped and called his buddy up on the phone.... hehe

Stuff like this amazes me about the Unimog that you can get a decent 404 with portal axles, the gear ratio and it runs for around $6000. I don't know how much people sink into their other rigs but I wish I would of found the Unimogs earlier before dumping thousands and thousands into other rigs.

I remember seeing Marlin's triple case truck with 1067: 1 or something like that, so i know that it can be done. However it doesnt seem that a mog gets it super low crawl ratio like this. Large trucks (Uhaul type trucks and Semi's) have super low gears, like 13:1 for first, but i dont think that a 404 would have that low of a gear for first, so I assume that is first and a basic reducer of some type that provides full time four wheel drive.

Then a crawler and or super crawler box are attached to the bottom of this transmission tcase combo?? From the link above, I see the lowest crawl ratio is about 350: 1 and that includes the 756 axle ratio. So how do you go from 350 to 1 to over 4000 to one. How do all the pieces and parts fit together and what does each one do?

I also found mention of a 16 speed tranny, a 20 speed tranny and another one that had some type of torque converter that acted like an auto after you go going. The clutch was used to stop and start and gears were bump shifted..

thanks

The 'cascade gear box' (the official name) is simply a pre-reduction box with 3 ratios internal. It attaches to the front of the transmission in place of a spacer. It has it's own shifter. That's how you can have a "16 speed" or "20 speed".

In a Gen II Unimog (406/416/ect), this gives you 6 forward speeds in 'normal' mode and FOUR (yes, four - 1/2/3/4, NOT 5 or 6) in each of the two crawler sets PLUS 2 reverse speeds in each of the three ranges, for a total of 20 speeds.

The torque converter option attaches in the same place as the cascade, so, unfortunatly, you can't have both. The T/C was used mostly on Mogs living life as rail car or airplane pullers.

A friend just bought a u500 so I was doing some research after driving it - truck trends article says the 24 speed is 3000-1 and covers 150 yards an hour at redline

The 'cascade gear box' (the official name) is simply a pre-reduction box with 3 ratios internal. It attaches to the front of the transmission in place of a spacer. It has it's own shifter.

so at the back of the engine you could have a cascade box with three ratios. The transmission, which has six speeds and an integrated transfer case of some type, attaches to this cascade box. I assume the torque tubes attach to the back and front of the transmission/transfer case combo.

On this page: http://www.unimogcentre.com/unimog406specs.html

a 43:1 is listed for super-low in the cascade box, awful deep, wonder how. If you use that 43:1 reduction and the low (combo) first gear of 14.53 and 6.52 axles, you get 4053 to 1 crawl ratio.

Anyone have info explaining the super low 43:1 in the cascade box or how the transmission with integral transfer case works?

Thanks for your help

The U500 transmission works like this:
The power comes in from a driveshaft from the clutch housing
It goes thru a 4spd gearbox with ratios 2.10, 1.51, 1.00, 0.736. From there is goes to a planetary range gear which reduce another 4.375 giving 1st = 9.57 and 8 total speeds.
From there there's a reverser which has a ratio 1.522 when selected. Reverse is locked out by computer in 7th and 8th, only in high range, unless you have the railway option.
From there it can go thru 2 planetary gear boxes, ratios 5.76 and 9.75, giving a net crawler gear ratio of 55.7, which multiplied by 5.92 axle gears and 9.57 main trans gearing is ~3200:1. I can match tire to winch speeds precisely with 4-6 crawler/reverse for rear winch, 3-5 crawler forward for front winch. So there are 24 forwards and 22 reverse speeds.
There is a function in the GS (transmission) computer linked to the MR (motor) computer which limits transmission output torque to 26000Nm, in other words rear wheel torque to ~115,000 ft-lb. It can be defeated using the Star Diagnostic System computer, but who'd want to?
The planetary working and crawler gear groups are not on the bottom of the transmission but the front passenger part of the gearbox.
The transmission is electro-pneumatically shifted and can optionally do it automatically with a M/A switch. It shifts to M automatically when in working or crawler gears. With this option the clutch pedal folds out of the way and clutch is actuated with servo mechanisms. There's a paddle with 2 function buttons. In M you go up or down but the clutch actuates automatically. With A it does it automatically but you can still trigger a shift with the paddle. The GS and MR and FR (chassis) computers prevent stupid things from happening like overspeeds. If you want to use the clutch pedal or the system screws up you pull a knob and the clutch pedal pops out. If the GS computer dies there's a rotary switch in the paddle housing that can pneumatically select N, 2R, 2 and 5. If the pneumatics die you're dead because you have no brakes but there are 3 bolts in the tool kit that can be screwed into certain holes in the gear box that can shift it into N, 2R or 2 for driving it to a safe spot or onto a lowboy. I suppose you could manually shift the range gear to high and tool down the road at 25mph in 5th if you slipped the clutch to get going (2.10 ratio).
It's not 1 inch per hour, it's like 1.6 inches/second (0.5"/sec at idle) in 1st crawler gear.

Charlie