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Mower transmissions

Posted by bus_driver (My Page) on
Tue, Jun 17, 14 at 13:42

Would like a discussion about transmissions. Back in the corner of the barn is an MTD (as best I remember) from long ago. 12 hp Briggs, 38" cut. The shift lever was simply forward and reverse plus a lever that moved a variable pulley to change ratios. Sort of an early variation of the CVT. MTD called it "Transmatic". Used the mower until the engine was well worn and the deck engagement lever/cutting height adjustment (all one lever) was about worn out. Ran that mower for at least 15 years. Not instant reverse, but it proved to be very durable.
Next was Murray Select with 21 or 22 hp and Peerless hydrostatic axle. The original axle lasted 11 years and the (absolutely new) replacement lasted just one year.
My Craftsman DYS4500 with TuffTorq axle scared me recently just before 300 hours but belt replacement seems to have cleared that problem.
It appears that the units Sears now advertises with travel speed of 7.5 mph must be the General CVT as the older ones with TuffTorq ( mine) were about 5.6 mph. Is this an easy way to identify the new transmission just from an ad?
Anyone here with user experience with the CVT?
One supposes that much testing was done prior to changing transmission suppliers. Reasons to change would be cost, durability, ease of use-- but I do not know how the CVT measures up in these categories.
I never have driven a CVT car. But more manufacturers are adopting them. I know one potential buyer who drove one and decided to just keep his old car.

"Be not the first by whom the new are tried, Nor yet the last to lay the old aside".

Alexander Pope

This post was edited by bus_driver on Sat, Jun 21, 14 at 16:31


Follow-Up Postings:

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RE: Mower transmissions

CVT transmissions seem to be gaining acceptance. The MTD versions of the last 40 years have had their quirks from an operator standpoint, but were certainly reliable. The new base D series Deere and some HOP models are the only ones I've ever worked on of the new generation and I still haven't done a drive repair. The HOP models must of come out 5 years ago or so. They may prove a good replacement for the entry level hydros. or not. We'll see...


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RE: Mower transmissions

Very interesting and helpful response. Thanks.
Yesterday I talked with a friend who has a mobile home park in which he uses the lower cost mowers. Says he has never had a transmission problem. One might assume that the mower owners who have experienced no problem will not be posting about transmissions.
I have had two failures of Peerless hydrostatic units. The differential is good in both of them. Before putting them in the scrap pile, I may disassemble them to see what is inside. I am familiar with the general operating principles of variable displacement hydraulic pumps.


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RE: Mower transmissions

My understanding is that the MTD CVT is a low-end unit that doesn't have much capability. For example, if you put a heavy cart behind it, or start pulling decent hills, it will burn up the belt quickly. The good news is that it is a lot cheaper to replace a belt than it is a new hydrostatic transmission.

I've also read that the General Transmission RS800 CVT is a much more robust unit than the MTD units. It is supposed to have capabilities approaching the TT K66 transmission, i.e., ground-engaging. If this is what Craftsman is truly putting in its go-fast lawn tractors that are sub-$2k, and if it stands up to the marketing hype, it will be a game-changer.

I am especially curious to see how the RS800 holds up, as I have a TT K46 approaching its end of life with just over 150 hours on it. If General Transmission makes it so we can retrofit the RS800 in place of the TT K46, they will have a real winner on their hands.


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RE: Mower transmissions

Here is General's website:

Here is a link that might be useful: General Transmission RS800


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RE: Mower transmissions

I did notice that John Deere uses a GT CVT in their entry-level D105 rider. I went to HD's website and combed over the reviews. There were mixed reviews regarding the transmission, with several folks having their riders in to the dealer for transmission servicing. So the jury is still out on these CVTs. However, none of the reviewers specifically mentioned the problem(s) they were having (some of these folks will take it to their servicing dealer if all they need is a belt replacement). Also, JD doesn't specify which transmission they use in the D105, but according to tractordata.com, it is the RT400, which is the lower end version, not the one Craftsman is using.

Some of the Ariens are apparently using the RS800, also (models 936075/76 and 936083/85), so might look at them for reviews. I would assume Husqvarna (maker of Craftsman riders) would also have some models with the RS800.


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RE: Mower transmissions

I just got an AYP with the 800 transmission and I love it. Yes, it can go very fast. It will go up a steep hill like a bulldozer and accelerate up it just fine. I love it. I don't see a need to buy a tractor with a hydro ever again. All the mnx you should have to worry about is a belt and two pulleys, and they are on the outside of the transaxle. No word on longevity as mine is new, but the old torque converter I had in a minibike and in my snowmobile that are very similar have been very reliable with a longer mnx period than any hydro.


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RE: Mower transmissions

Interestingly, John Deere presently uses hydrostatic drive on their harvesting machines, which often are called "combines". For a time in the past, they used variable speed belt drives. The hydrostatic has the advantages of being able to put a motor at each wheel. No need to try to route a shaft through the machine where some other crop-handling components also are located.


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