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Message |
Joel N-Cal (64.142.48.67)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, February 16, 2004 - 5:12 pm: | |
Anyone interested in joining a group buy on differential gearing for MAN planetary differentials please contact me via the above link to my email. Use "differential" in the subject line.
Joel N-Cal
85 MAN |
Jason Windecker (198.81.26.45)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, February 17, 2004 - 3:42 am: | |
I'v got a man differential housing for sale and possibly some differential gearing parts, i will have to take a look, also many many man parts. transmissions, ETC, let me know if your interested
Jason Windecker
Businjay@aol.com |
Phil Dumpster (24.16.189.48)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, February 17, 2004 - 10:38 am: | |
You know, I have a hunch that if you remove the planetary carrier from one side and replace it with a solid piece to remove the gear reduction, it would have the same effect that you are after, namely increase the top speed of the coach.
I suspect the Metro coaches were delivered that way, then later changed as they aged and were no longer in county service. They were dog slow when delivered. |
Joel N-Cal (64.142.48.67)
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Votes: 0 (Vote!) | | Posted on Tuesday, February 17, 2004 - 11:20 am: | |
Phil
That's an interesting idea, however it sure would be hard on the spider gears.
In fact I am working on a source of gearing which will replace the Ring an Pinion an achive a 3.70 ratio. This will allow a MAN differentials with bus tires to run at 65 MPH at approximately 1900 RPM.
Joel N-Cal |
Phil Dumpster (24.16.189.48)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, February 18, 2004 - 5:59 am: | |
What is the reduction ratio of the planetary hubs? Perhaps you could remove both of them.
I doubt it would be too hard on the spider gears, they are under stress anyway on acceleration. City transit busses rarely go in a straight line for most of the mileage they rack up in their service lives. If these were limited-slip differentials that's one thing, but every transit I've ever seen had a completely open differential.
The only downside I see is in snow or ice, the side with the active gears in the hub would probably have a tendency to break free and lose traction.
By the way, this coming May Seattle will be auctioning off the rest of their MAN fleet as well as the rest of the MAN parts inventory. |
Joel N-Cal (64.142.48.67)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, February 18, 2004 - 3:42 pm: | |
Phil,
The reduction on the MAN planetaries is 3.48:1
MAN axles achive their reduction with both the Ring and Pinion and the Hubs. Most of the units I know of have a 5.22 to 1 overall ratio which is attained by combining the 3.48 with a 1.5 to 1 ring and pinion. 1.5 X 3.48 = 5.22 If you remove one hub unit the other will still requre 3.48 turns of the axle per rotation of the tire while the other axle will rotate one turn per tire rotation. The resulting overall ratio of 1.5 x 3.48/2 = 2.61 will allow a 2200 RPM cruising speed of 106.58 MPH and a 65 MPH at 1342 RPM. Not what I call a practical ratio.
MAN offers a mechanical lock which direct locks both wheel together, eliminating the spiders. This is a in or out coupling.
Joel N-Cal
85 MAN Transit |
Phil Dumpster (24.16.189.48)
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Votes: 0 (Vote!) | | Posted on Friday, February 20, 2004 - 6:47 am: | |
I'm aware of the dual reduction system on the MAN drive axle. It's one of the things that gives that coach it's characteristic "note" when moving down the road.
You calculations would be valid if the side with zero reduction was held to zero RPM. Then the left wheel would exhibit a ratio of 2.61, which is half of 5.22.
A differential is a power splitter. If both sides have the same ratio, the power split is 50-50. With one side at 1:1 and the other at 3.48:1, the split becomes 78-22, in favor of the side with the reduction.
78% of 3.48:1 is 2.71. 22% of 1:1 is, of course, 1.
Taking into consideration the 1.5:1 ring-and-pinion ratio, the final drive ratio becomes 4.07.
While that would be an improvement, the bigger problem becomes the power split. 78% of the power that moves the coach goes through the side with the reduction. On dry pavement, this probably won't be that much of a problem. I doubt it would hurt the tires although they would probably wear out faster. On any kind of slippery surface, however, that side will tend to slip very easily.
Here's another thought, depending on the cost of replacing gearsets. I wonder if a rear axle from a Gillig would fit? That would get you down the road and be quieter than the MAN axle. You'd end up with two different styles of wheels front and back, but that shouldn't be a problem. |
Joel N-Cal (64.142.48.67)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, February 20, 2004 - 2:14 pm: | |
Phil,
While I do not agree with your numbers, the fact remains that removing a hub is not an economic reality. The axle housings unusual shape and clearance makes it prohibitive to convert to another type differential. MAN has indicated that they will sell upgrade gears and bearing for about $1500. Even with the cost of having a gear shop install the new gears, it is still less expensive and much more reliable than the aforementioned alternatives not to say anything about the hassle.
Most transits with large hubs are MAN differentials. Hopefully some of the current owners of these units will join me in upgrading.
While MAN offers one alternative, after market manufactures may offer another. These alternatives are currently being explored.
Joel N-Cal
85 MAN Transit |
BrianMCI96A3 (65.40.246.48)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, February 20, 2004 - 9:32 pm: | |
"22% of 1:1 is, of course, 1."
Really...
Dat's dat dere NEW math, ain't it!
(grin)
Brian |
Phil Dumpster (24.16.189.48)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, February 21, 2004 - 7:12 am: | |
Actually, found another reason why removing one of the hub planetary gears wouldn't work - turns out the axle half shaft turns in the opposite direction from the wheel! Those planetary gearsets also reverse the direction of rotation.
3.48 would mean the sun gear has 25 teeth and the ring gear has 87. The planet carrier is held stationary by the axle housing, so the number of teeth on the planet gears does not figure into the equation.
No, you wouldn't be able to put a different differential into the MAN housing. I was alluding to changing over to a hypoid housing.
If MAN is willing to sell you a set of gears for $1500, take it. I doubt you're going to be able to do anything else to achieve a lower numeric gear ratio for any less than that, unless you have the machinery to cut your own gears.
Even then, it seems strange to design the system to require changing the differential ring and pinion when a gear change could be accomplished by changing the reduction at the hubs. It would seem that a gear change (for a different service profile) would be easier that way.
Well, go figure. German engineers always did seem to sing from a different songbook from everyone else.
By the way, found out the ZF 5HP series transmission is also available in a version which will bolt up to the MAN 2566 engine, so if your Renk ever dies on you there is another option. |
Joel N-Cal (64.142.48.67)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, February 21, 2004 - 1:43 pm: | |
Phil,
Thanks for the additional information on the hubs. MAN offers little technical data publicly and my limited network has no one with MAN differential knowledge. Should you care to share you data source it would be appreciated.
I have located some after-market suppliers who can supply parts for the 8 ton H07 and H09 differentials. Unfortunately their reference material does not include the heavier 10, 11, and 13-ton units. Therefore we must to cross reference to match. If we can do it, the cost should drop to under $500 per unit, on an individual buy level.
Joel N-Cal
85 MAN Transit |
Phil Dumpster (24.16.189.48)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, February 21, 2004 - 11:05 pm: | |
You may have to look overseas where MAN still does business. They are a popular make outside of North America.
I'll do some more asking around to see if I can turn up some more information. |