My Tractor Forum banner

1 - 13 of 13 Posts

·
Registered
Joined
·
15 Posts
Discussion Starter #3
Thanks I thought some had hydrostats the ones with the foot peddle.
I was wrong? the peddle is just for f/r in that gear like the lever?

Thanks Paul B
Brian
 

·
Banned
Joined
·
131 Posts
Conventional 4 wheel, belly mower, GRAVELY riding tractors like the 7173-H, GEM & some 1200 Series have hydrostatic drive. These smaller GRAVELY tractors have the "hydrostats" control lever to the right of the seat. Their foot pedal on right is the brake.

GRAVELY's larger Professional-G Series riding tractors are all gear drive & the foot pedal at right controls external dry clutches that provide instant forward/reverse. Applying the brake pedal(s) on left disengages the forward/reverse clutches. The big foot pedal on right replaced the earlier long lever, on right side/in front of steering wheel used on 8000, 800 & 400 series riders. None of these had hydrostatic trans.
 

·
Registered
Joined
·
310 Posts
"Did Gravely use a hydrostatic trans?"

No. Looking at my 21-year old Gravely catalog that came with my 1988 Professional 12-G 4-wheel tractor. They appear to have built essentially the same machine with both GEAR drive and HYDROSTATIC drive. They ended their gear-drive model names with letter "G," whereas they ended their hydrostatic-drive model names with letter "H."

If you examine gear sets fitted into Gravely gear boxes, you might think that you were looking at automotive transmission power-range gears made to transfer more than 100 horsepower. They are EXTREMELY robust compared to equipment that sold for much lower original prices. I am not willing to disassemble the manual transmissions in my Gravely 9000, Gravely Professional 12-G, Kubota B5100D 4-wheel drive diesel, and 38" cut "Ranch King" to make side-by-side comparisons. But my expectation, based on seeing some other examples that were disassembled, is that the Gravely gear boxes are more strongly built than the others. My other riders, an Ariens S16-H with 60" mowing deck, a John Deere 317 with mowing deck, and Toro 322-D with 72" mowing deck all have hydrostatics. Every time I use one of them, I feel that I'm tempting fate as I don't believe any hydrostatic is comparably robust verses a good gear box. A great manual transmission in a car or pickup should run at least 1,000,000 miles without any more service than lubrication maintenance. The same cannot be said about automatics. I feel hydrostatics are comparable to owning an automatic car transmission. If you use it enough hours, it is likely to need much more expensive maintenance than a manual gear box.

I also have a Snapper 5-speed rider which actually has no gear box. Its motor spins an aluminum disk with a hollow center section. The 5-forward speeds are obtained by rolling against the aluminum drive disk, a hard-rubber-edged wheel on spinning on a 90-degree different axis. Its neutral is obtained by positioning the rubber wheel over the spinning aluminum drive disk's hollow center section. That way they don't touch each other. Forward speed selection just selects a linkage notch that moves the rubber wheel further from the spinning drive disk's center. Obviously, top gear contact patch is toward the outside of that spinning disk. Reverse is obtained by sliding the rubber power-collection wheel to the other side of the driving disk's spin axis. This configuration doesn't sound like it would be durable. Yet these goofy multi-speed drives enjoy a good reputation for durability.

One kind of hysteresis is internal friction with elastic bodies. Imagine how the rubber power-collection wheel is deformed as it contacts the spinning aluminum disk drive wheel's various selectable diameters. The rubber power-collection wheel is forced to deform more and more as lower speed ratios are selected. Consider how auto tires roll along straight roads without being forced to flex and squirm side to side. But when they are forced to turn from that straight line, it's directional path is continually changing until the new straight line path is established. During turns, auto tires generate lots of hysteresis internal friction. The sharper the turn, them more internal friciton. Snapper's rubber driven wheel is also subject to that same internal flexing. It converts part of input power to waste heat from internal hysteresis friction. The sharper the turn, the worse this friction becomes. Run a Snapper Rear Engine Rider in its "1st gear" position, and that little rubber power-collection wheel is forced to generate a LOT of hysteresis power loss because is is continually turning sharply. So this strange transmission's efficiency increases with every upward shift due to lower friction losses.

This may be more than you wanted to know about some of the many drive configuration options fitted to rider mowers. I have NOT described all driving systems I've seen or considered. Electric drives would probably be much more durable, more efficient, never leak, and provide other advantages compared to hydrostatic drives.

My personal order of preference would be:
Most preferred -continuously-variable-speed & direction DC electric drive
Next most preferred - All gear drives
Least preferred -
hydrostatic low-efficiency failure-prone often leaking drives
and
progressive mechanical-slipping variable-ratio drives like Snapper RER and variable-size pulley drives.

No transmission which converts a big percentage of input power to waste heat is a friend of mine. Others clearly are not offended by that kind of waste.

Others have their own preference orderings for their own reasons.
John
 

·
Premium Member
Joined
·
8,051 Posts
My 5660 was a shuttle type trans just like large tractors use. Select range, gear and clutch fwd rev not shifting. Very efficient and powerful system.
IMO the best for any tractor. Does not use as much of the engines HP as a hydro.

MU
 

·
Banned
Joined
·
131 Posts
"No." Say what!? The '88 GRAVELY catalog describes the hydrostatic Professional-H, 'Stand Alone' model 18-H, that had a grille & hood resembling the Professional-G Series, BUT any similarity ends right there. These are definitely NOT "essentially the same machine(s)" & nobody should confuse an 18-H w/the 18-G, as if it were a choice of an optional transmission. These tractors are not models in the same series. The 18-H has a front engine, totally different frame & seat platform, miniature 3-point hitch & unique belly mower.

"Did Gravely use a hydrostatic trans?"

No. Looking at my 21-year old Gravely catalog that came with my 1988 Professional 12-G 4-wheel tractor. They appear to have built essentially the same machine with both GEAR drive and HYDROSTATIC drive. They ended their gear-drive model names with letter "G," whereas they ended their hydrostatic-drive model names with letter "H."
GRAVELY's smaller 1200 Series did use "both GEAR drive and HYDROSTATIC drive" & the 5 models were "essentially the same machine" defined by their motors & trannys.
 

·
Registered
Joined
·
15 Posts
Discussion Starter #8
Thanks all of you! your input is welcome!
I thought the ones with a pedal on the right instead of a lever where
hydro. My bad.
I Like the trans it lets me run WOT and fast on the flats and slow on the slopes
when I am cutting and fast in the shallow snow and slow in the drifts.
All running the motor flat out or should I say up to the governor.
Never used anything put. 26 years cutting and plowed 3 years with one,
blowing snow the rest with wheel horse she is now getting old and like the gravels LCG for the slopes.
I have lost the splines on the axles and welded the spiders back on, broke
the center out of the left wheel that's down slope, bent the blower on bad sidewalk and cold patch the town throws down in Nov than plows up on to the walk first snow.
Never had a trans leak squeak or any other trouble.
Sorry if the speeleleelignggnn is off.
Beny PS Thanks all for your input.
PSS Do you shift on the flats and the slopes?

TIERED OF RIDING MY HORSE SIDE SADDLE!:biglaugh:
 

·
Registered
Joined
·
310 Posts
Apparently I misread the original question, which was
"Hi all Did Gravely use a hydrostatic trans?"
For some reason I thought it said, "Hi did all Gravelys use a hydrostatic trans?"

I used copy and paste, removing only the "Hi."
My apologies for any confusion that caused. Clearly I responded to the question based on my misreading. My answer to the original question is Yes.

I described Gravely's model naming convention where "H" = hydrostatic and "G" = gear.
John
 

·
Registered
Joined
·
15 Posts
Discussion Starter #10
Hi LoveLearn I know how you fell about my spelling so do us booth a favor and don’t respond to anything I post. OK
Thanks Beny
PS your post was so long I did not read it all anyway. But thanks.
 

·
Collector of many tractors
Joined
·
15,270 Posts
"Did Gravely use a hydrostatic trans?"

No. Looking at my 21-year old Gravely catalog that came with my 1988 Professional 12-G 4-wheel tractor. They appear to have built essentially the same machine with both GEAR drive and HYDROSTATIC drive. They ended their gear-drive model names with letter "G," whereas they ended their hydrostatic-drive model names with letter "H."

If you examine gear sets fitted into Gravely gear boxes, you might think that you were looking at automotive transmission power-range gears made to transfer more than 100 horsepower. They are EXTREMELY robust compared to equipment that sold for much lower original prices. I am not willing to disassemble the manual transmissions in my Gravely 9000, Gravely Professional 12-G, Kubota B5100D 4-wheel drive diesel, and 38" cut "Ranch King" to make side-by-side comparisons. But my expectation, based on seeing some other examples that were disassembled, is that the Gravely gear boxes are more strongly built than the others. My other riders, an Ariens S16-H with 60" mowing deck, a John Deere 317 with mowing deck, and Toro 322-D with 72" mowing deck all have hydrostatics. Every time I use one of them, I feel that I'm tempting fate as I don't believe any hydrostatic is comparably robust verses a good gear box. A great manual transmission in a car or pickup should run at least 1,000,000 miles without any more service than lubrication maintenance. The same cannot be said about automatics. I feel hydrostatics are comparable to owning an automatic car transmission. If you use it enough hours, it is likely to need much more expensive maintenance than a manual gear box.

I also have a Snapper 5-speed rider which actually has no gear box. Its motor spins an aluminum disk with a hollow center section. The 5-forward speeds are obtained by rolling against the aluminum drive disk, a hard-rubber-edged wheel on spinning on a 90-degree different axis. Its neutral is obtained by positioning the rubber wheel over the spinning aluminum drive disk's hollow center section. That way they don't touch each other. Forward speed selection just selects a linkage notch that moves the rubber wheel further from the spinning drive disk's center. Obviously, top gear contact patch is toward the outside of that spinning disk. Reverse is obtained by sliding the rubber power-collection wheel to the other side of the driving disk's spin axis. This configuration doesn't sound like it would be durable. Yet these goofy multi-speed drives enjoy a good reputation for durability.

One kind of hysteresis is internal friction with elastic bodies. Imagine how the rubber power-collection wheel is deformed as it contacts the spinning aluminum disk drive wheel's various selectable diameters. The rubber power-collection wheel is forced to deform more and more as lower speed ratios are selected. Consider how auto tires roll along straight roads without being forced to flex and squirm side to side. But when they are forced to turn from that straight line, it's directional path is continually changing until the new straight line path is established. During turns, auto tires generate lots of hysteresis internal friction. The sharper the turn, them more internal friciton. Snapper's rubber driven wheel is also subject to that same internal flexing. It converts part of input power to waste heat from internal hysteresis friction. The sharper the turn, the worse this friction becomes. Run a Snapper Rear Engine Rider in its "1st gear" position, and that little rubber power-collection wheel is forced to generate a LOT of hysteresis power loss because is is continually turning sharply. So this strange transmission's efficiency increases with every upward shift due to lower friction losses.

This may be more than you wanted to know about some of the many drive configuration options fitted to rider mowers. I have NOT described all driving systems I've seen or considered. Electric drives would probably be much more durable, more efficient, never leak, and provide other advantages compared to hydrostatic drives.

My personal order of preference would be:
Most preferred -continuously-variable-speed & direction DC electric drive
Next most preferred - All gear drives
Least preferred -
hydrostatic low-efficiency failure-prone often leaking drives
and
progressive mechanical-slipping variable-ratio drives like Snapper RER and variable-size pulley drives.

No transmission which converts a big percentage of input power to waste heat is a friend of mine. Others clearly are not offended by that kind of waste.

Others have their own preference orderings for their own reasons.
John
Two more neat var-speed boxes is...

Zero-max... you got to see there video to see how this works...
And...
Reeves-drive var-drive with slots cut in the pully face with a chain belt that changes shape...

http://en.wikipedia.org/wiki/Continuously_variable_transmission
 

·
Registered
Joined
·
29 Posts
LoveLearn,
Please respond to any of my posts! Good explaination on the snapper. I have a snapper RER but never really thought about the speed control. I prefer simple low waste transmissions like gear drive also.
 

·
Moderator
Joined
·
22,114 Posts
LoveLearn and landreo

I fully agree that a hydrostatic transmission is substantially less efficient than a gear transmission, however, with the current crop of overpowered lawn and garden tractors which don't have the weight to make use of even half of their horse power, I think the point is moot. In 27 years and well over 2000 hours of brutal loader work, the only damage the hydro in my 2000+ pound MF1655 sustained occured after parts failed in the gearbox and chewed up the inside of the gear case. A gear drive could not deliver more power to the rear wheels, since the rear tires were equiped with chains and still dug holes, even with the front wheels in the air. Speed control and forward /reverse shifting are the all important bonuses with hydro.

Tractors are rated as PTO horsepower, which is less than engine horsepower, to let you know how big a lawn mower or snowblower you can operate effectively. At 4 or 5 mph, it doesn't take more than 5 horsepower to move even 2000 lbs of tractor on level ground, even with a hydro.

Just my thoughts and observations.

Bob
 
1 - 13 of 13 Posts
Top