Hydrostatic taps only portion of engine total power for the wheels. Pulling/pushing capability is limited by design.
300 series -8 vs. Hyrdo
assuming the same horsepower in a 300 series toro/wheel horse, is there anything the 8speed gear drive can do that the hydro can't ?
Does the hydro drive restrict the tractors abilities at all ?
thanks
Does the hydro drive restrict the tractors abilities at all ?
thanks
1 - 13 of 13 Posts
Assuming that the hydro has the same 2-speed final drive as the gear drive, then the following is correct. If it doesn't, then the following is a comparison for HI range of the gear drive only.
Hydros typically produce 20% less horsepower at the rear wheels than a gear drive for a given engine horsepower. That being said, it is a rare occasion when the wheels have enough traction to make use of even the lesser resulting horsepower. The difference will show up when pulling a heavy load up a slope at top speed.
The flip side is that hydros typically produce more axle torque at less than WOT. How much torque depends on the size of the hydro.
The main benefit of a hydro is torque generation to start a load in motion. It produces a relatively flat torque curve from just above idle to near maximum engine speed which can be measurably higher than that produced by a gear drive at WOT in the lowest gear. A 12 hp GT can pull a 3600 lb travel trailer starting at idle and advancing to WOT and top speed in about 15'. A gear drive cannot do that because it can't start the load in motion in the highest gear due to the lack of available torque at idle.
A gear drive makes its maximum axle torque at WOT of the engine and multiplied by the gear reduction. A hydro makes its torque in the hydro motor by motor displacement and the hydraulic pressure required to move the load and that is multiplied by the gear reduction to get the maximum axle torque. There is no direct relation between engine torque and the torque applied at the rear axle until the engine, and tractor, approach maximum speed.
The main benefits of a gear drive are consistent travel speed, and more horsepower available in high gear at WOT.
Again, hydro size (displacement) is the governing factor when comparing the relative merits. The problem with such comparisons is the traction required to keep the wheels from spinning at the high axle torque values.
The hydros at the top end of GT applications can develop axle torque numbers big enough to break the 1250 ft-lb rated final drives if sufficient traction is available.
Hydros typically produce 20% less horsepower at the rear wheels than a gear drive for a given engine horsepower. That being said, it is a rare occasion when the wheels have enough traction to make use of even the lesser resulting horsepower. The difference will show up when pulling a heavy load up a slope at top speed.
The flip side is that hydros typically produce more axle torque at less than WOT. How much torque depends on the size of the hydro.
The main benefit of a hydro is torque generation to start a load in motion. It produces a relatively flat torque curve from just above idle to near maximum engine speed which can be measurably higher than that produced by a gear drive at WOT in the lowest gear. A 12 hp GT can pull a 3600 lb travel trailer starting at idle and advancing to WOT and top speed in about 15'. A gear drive cannot do that because it can't start the load in motion in the highest gear due to the lack of available torque at idle.
A gear drive makes its maximum axle torque at WOT of the engine and multiplied by the gear reduction. A hydro makes its torque in the hydro motor by motor displacement and the hydraulic pressure required to move the load and that is multiplied by the gear reduction to get the maximum axle torque. There is no direct relation between engine torque and the torque applied at the rear axle until the engine, and tractor, approach maximum speed.
The main benefits of a gear drive are consistent travel speed, and more horsepower available in high gear at WOT.
Again, hydro size (displacement) is the governing factor when comparing the relative merits. The problem with such comparisons is the traction required to keep the wheels from spinning at the high axle torque values.
The hydros at the top end of GT applications can develop axle torque numbers big enough to break the 1250 ft-lb rated final drives if sufficient traction is available.
Hydrostatic system contains these core parts: hydraulic pump, hydraulic motor, gear reducer/differentials.
The system converts mechanical energy into fluid dynamics for home lawn garden implementation.
Per law of conservation of energy, output at the wheels can't be greater than the input source.
Below assume 100% efficiency with no loss between stages.
How much HP is sent to the wheels, look at the pump specs:
Max HP = Max GPM x Max PSI / 1714.
In my 19.5HP JD LA115,
pump/motor is: 7/10 CC
input shaft max revolution: 3000 RPM
max pump PSI: manufacturer does not publish. My wild guess is 3000 PSI (say, governed by a relief valve)
convert cc to GPM: (0.007 * 3000) / 3.785 = 5.548 GPM
HP = 5.548 * 3000 / 1714 = 9.71 HP.
If I try to upgrade to 23HP engine thinking it will help me push snow or pull heavier load, it won't.
By design, only 10HP is used.
The system converts mechanical energy into fluid dynamics for home lawn garden implementation.
Per law of conservation of energy, output at the wheels can't be greater than the input source.
Below assume 100% efficiency with no loss between stages.
How much HP is sent to the wheels, look at the pump specs:
Max HP = Max GPM x Max PSI / 1714.
In my 19.5HP JD LA115,
pump/motor is: 7/10 CC
input shaft max revolution: 3000 RPM
max pump PSI: manufacturer does not publish. My wild guess is 3000 PSI (say, governed by a relief valve)
convert cc to GPM: (0.007 * 3000) / 3.785 = 5.548 GPM
HP = 5.548 * 3000 / 1714 = 9.71 HP.
If I try to upgrade to 23HP engine thinking it will help me push snow or pull heavier load, it won't.
By design, only 10HP is used.
The Tuff Torq T40 in the JD LA115 is the precursor of the K46. By back tracking the math from the specced axle torque (171 ft-lb) through the gear reduction (28.04:1), the motor torque (73.18 in-lb) can be found. With the motor torque (73.18 in-lb) and motor displacement (0.0.61024 cu-in), the pressure (753 psi) can be found.
With a maximum rated input of 3400 rpm, a 0.4272 cu-in (7 cc) pump will flow 6.29 gpm.
Horsepower required (3.15 hp) = Flow (6.29 gpm) X Pressure (753 psi) / 1500
Horsepower available at the rear axle will be about 15-20% less.
References:
https://www.tufftorq.com/product/k46/
With hydraulics, there is always a loss of power transmission due to the need for clearances to lubricate the moving parts. As the pressure increases, so goes the loss due to the higher flow rate of pumped fluid through those clearances, hence the use of a Rule of Thumb with a divisor of 1500 for horsepower calculations rather than the more correct divisor if 1714 for theoretical calculations.
The transmission will perform to its maximum capability with a 5 hp engine, to allow for losses with the drive belt and charging system. The implements used on the tractor are where the large horsepower numbers are required.
There is only one hydro transmission used in GTs capable of surviving 3000 psi, the Sundstrand Series 15, which is used in mostly medium to heavy GTs.
Axle torque is what is used to get the load in motion and provide acceleration. Torque, in and of itself, does not imply motion. Horsepower is used to maintain the speed achieved by the torque. Applying 75 ft-lb of torque to a bolt torqued to 80 ft-lb does not result in motion.
With a maximum rated input of 3400 rpm, a 0.4272 cu-in (7 cc) pump will flow 6.29 gpm.
Horsepower required (3.15 hp) = Flow (6.29 gpm) X Pressure (753 psi) / 1500
Horsepower available at the rear axle will be about 15-20% less.
References:
https://www.tufftorq.com/product/k46/
Relationship between displacement and torque of a hydraulic motor
T = D x PSI ÷ 24π
T is torque in foot-lbs; D is displacement in cubic inches per revolution; PSI is pressure difference across motor; π = 3.14
Rules–of–thumb
Horsepower for driving a pump
For every 1 HP of drive, the equivalent of 1 GPM @ 1500 PSI can be produced.
Many hydros do not have a relief valve. They rely on wheel spin as a pressure limiter.Hydraulic (fluid power) horsepower
HP = PSI x GPM ÷ 1714
PSI is gauge pressure in pounds per square inch; GPM is oil flow in gallons per minute
With hydraulics, there is always a loss of power transmission due to the need for clearances to lubricate the moving parts. As the pressure increases, so goes the loss due to the higher flow rate of pumped fluid through those clearances, hence the use of a Rule of Thumb with a divisor of 1500 for horsepower calculations rather than the more correct divisor if 1714 for theoretical calculations.
The transmission will perform to its maximum capability with a 5 hp engine, to allow for losses with the drive belt and charging system. The implements used on the tractor are where the large horsepower numbers are required.
There is only one hydro transmission used in GTs capable of surviving 3000 psi, the Sundstrand Series 15, which is used in mostly medium to heavy GTs.
Axle torque is what is used to get the load in motion and provide acceleration. Torque, in and of itself, does not imply motion. Horsepower is used to maintain the speed achieved by the torque. Applying 75 ft-lb of torque to a bolt torqued to 80 ft-lb does not result in motion.
Great info, thanks!The Tuff Torq T40 in the JD LA115 is the precursor of the K46. By back tracking the math from the specced axle torque (171 ft-lb) through the gear reduction (28.04:1), the motor torque (73.18 in-lb) can be found. With the motor torque (73.18 in-lb) and motor displacement (0.0.61024 cu-in), the pressure (753 psi) can be found.
With a maximum rated input of 3400 rpm, a 0.4272 cu-in (7 cc) pump will flow 6.29 gpm.
Horsepower required (3.15 hp) = Flow (6.29 gpm) X Pressure (753 psi) / 1500
Horsepower available at the rear axle will be about 15-20% less.
References:
https://www.tufftorq.com/product/k46/
Many hydros do not have a relief valve. They rely on wheel spin as a pressure limiter.
With hydraulics, there is always a loss of power transmission due to the need for clearances to lubricate the moving parts. As the pressure increases, so goes the loss due to the higher flow rate of pumped fluid through those clearances, hence the use of a Rule of Thumb with a divisor of 1500 for horsepower calculations rather than the more correct divisor if 1714 for theoretical calculations.
The transmission will perform to its maximum capability with a 5 hp engine, to allow for losses with the drive belt and charging system. The implements used on the tractor are where the large horsepower numbers are required.
There is only one hydro transmission used in GTs capable of surviving 3000 psi, the Sundstrand Series 15, which is used in mostly medium to heavy GTs.
Axle torque is what is used to get the load in motion and provide acceleration. Torque, in and of itself, does not imply motion. Horsepower is used to maintain the speed achieved by the torque. Applying 75 ft-lb of torque to a bolt torqued to 80 ft-lb does not result in motion.
BTW, I got 3000RPM number from kanzaki link
IHT Transaxle series K (K46, K57, K58, K62, K66, K72)?Hydraulic Equipments,Transmissions and Marine Gears?Products?Kanzaki Kokyukoki Mfg. Co., Ltd.
I keep thinking about this. There could be one, a discrete one. Seen in YT videos, the motor is loosely pressed against the pump by its piston springs. If the pressure is too high exceeding combined piston spring rate, the fluid would push the motor casing away, breaking the fluid channel. Is it?Many hydros do not have a relief valve. They rely on wheel spin as a pressure limiter.
Not really. The pump and motor cartridges bear on valve plates in the center section with drilled passages behind the valve plates to direct the fluid. There is sufficient spring pressure to ensure a seal between the cartridges and the valve plates without causing excessive wear.
If there is a relief valve, it will be in the center section between the pump and motor and it will operate in both forward and reverse. Depending on the nomenclature used by the various companies, these are known as either acceleration valves, or cross-over relief valves, and are meant more for reducing shock loads to the rest of the drive train if the drive control is moved aggressively from one direction to the other. To the best of my knowledge, this feature is not included in the hydros used in LTs and light GTs. It is used in the high performance hydros used in heavy GTs where horsepower at the rear wheels can exceed engine output momentarily before the engine stalls.
If there is a relief valve, it will be in the center section between the pump and motor and it will operate in both forward and reverse. Depending on the nomenclature used by the various companies, these are known as either acceleration valves, or cross-over relief valves, and are meant more for reducing shock loads to the rest of the drive train if the drive control is moved aggressively from one direction to the other. To the best of my knowledge, this feature is not included in the hydros used in LTs and light GTs. It is used in the high performance hydros used in heavy GTs where horsepower at the rear wheels can exceed engine output momentarily before the engine stalls.
All that's good to know, but I was kinda wanting to hear from anybody with firsthand experience with a 300 series 10,12 or 14horse with both the hydro version and also one with the 8speed gear drive.
I've got a 314-8 that I use for hauling/pulling small cart for occasional yard clean up, and then annually pulling an aerator with a few hundred pounds of lead bricks. Would a 314-hydro be as capable ?
I've got a 314-8 that I use for hauling/pulling small cart for occasional yard clean up, and then annually pulling an aerator with a few hundred pounds of lead bricks. Would a 314-hydro be as capable ?
./////////////////////////////////////All that's good to know, but I was kinda wanting to hear from anybody with firsthand experience with a 300 series 10,12 or 14horse with both the hydro version and also one with the 8speed gear drive.
I've got a 314-8 that I use for hauling/pulling small cart for occasional yard clean up, and then annually pulling an aerator with a few hundred pounds of lead bricks. Would a 314-hydro be as capable ?
Yes--speaking as a W/H owner (older versions)--"C" models--120A/1120 8 sp.--I use my C120-A all the time for yard duties--I like the creep effect of the hydro vs, coming to an abrupt stop to shift gears. I aerate/pull a seeder and occassionally use a center moldboard blade for spreading dirt or whatever. For me--the Hyrdo works much smoother.
Do not cut grass with this, however--I use a newer XT2Cub with bagger.
Hope this helps-
glenn
Another WH owner here who has used many hydros and a couple gear...
If you rototill, the tiller will "push" a hydro a bit more than a gear (provided no drive belt slippage). The 2 speed rear end gives the gear drive a nice creeper gear, but as pointed out, you need to stop and change gears to go faster.
The hydros in the 300 series don't tend to burn up like some of the lower line transmissions in box store LTs (Wheelhorse uses Eaton 700 or something like that, if I recall correctly).
I much prefer the hydros, especially for mowing and snowblowing... So much easier to slow down/speed up for changing grass heights and snow depths, and for changing direction.
The gear models definitely seen to have more pulling power for the reasons TUDOR mentioned, but taking off going up a hill, or trying to get to top gear with gear drive is tough. If you have a heavy pull, you're starting out on level ground, and if you finish the pull on level ground, the gear drive may prevail (think skidding logs uphill with unlimited traction). I think the gear drive models are a touch faster top speed wise, but it really isn't much.
For about everything I do with my machine (mow, pull light loads, snowblow, aerate), I chose hydro every time and have never felt limited.
One thing I forgot to mention - if I was pulling a several hundred pound lawn roller, I'd probably go with the gear transmission, just to save wear on my hydro. I straight line might be OK, but turning those things around puts a strain on the machine.
A more direct answer to the OP's question - there is practically nothing a WH 300 series gear drive will do that a hydro will not do. However, a hydro will do many things very easily that a gear drive cannot do very easily.
Get the 314 Hydro. You won't miss your gear drive.
Running Wheelhorse machines I've owned and used that qualify me to answer the question:
308-8, 310-8, 312-8, 315-8, 312-A (multiple) 314-A, 212-5, A-100, B-100 automatic, C-125 automatic, C-120 black hood 8 speed, 414-8, 520-H (multiple), 520-HC (multiple), 518-H, 416-A, and probably others that are escaping me at the moment...
My go-to machine has always been the 312-A. It could use a couple extra horsepower (your 314-H would be good) to run the 2 stage blower (minimum HP I'd be comfortable running with) and the 48" deck with powerflow bagger.
My ideal machine would have been a 520-H, due to gear reduction steering, heavy duty front end, and ability to take a 60" deck. But I bought and sold a lot of them and wasn't smart enough to keep one. I don't have as much for a GT any more now with a lot of acreage, but I'll always keep my 312-A with its original accessories for sentimental reasons.
If you rototill, the tiller will "push" a hydro a bit more than a gear (provided no drive belt slippage). The 2 speed rear end gives the gear drive a nice creeper gear, but as pointed out, you need to stop and change gears to go faster.
The hydros in the 300 series don't tend to burn up like some of the lower line transmissions in box store LTs (Wheelhorse uses Eaton 700 or something like that, if I recall correctly).
I much prefer the hydros, especially for mowing and snowblowing... So much easier to slow down/speed up for changing grass heights and snow depths, and for changing direction.
The gear models definitely seen to have more pulling power for the reasons TUDOR mentioned, but taking off going up a hill, or trying to get to top gear with gear drive is tough. If you have a heavy pull, you're starting out on level ground, and if you finish the pull on level ground, the gear drive may prevail (think skidding logs uphill with unlimited traction). I think the gear drive models are a touch faster top speed wise, but it really isn't much.
For about everything I do with my machine (mow, pull light loads, snowblow, aerate), I chose hydro every time and have never felt limited.
One thing I forgot to mention - if I was pulling a several hundred pound lawn roller, I'd probably go with the gear transmission, just to save wear on my hydro. I straight line might be OK, but turning those things around puts a strain on the machine.
A more direct answer to the OP's question - there is practically nothing a WH 300 series gear drive will do that a hydro will not do. However, a hydro will do many things very easily that a gear drive cannot do very easily.
Get the 314 Hydro. You won't miss your gear drive.
Running Wheelhorse machines I've owned and used that qualify me to answer the question:
308-8, 310-8, 312-8, 315-8, 312-A (multiple) 314-A, 212-5, A-100, B-100 automatic, C-125 automatic, C-120 black hood 8 speed, 414-8, 520-H (multiple), 520-HC (multiple), 518-H, 416-A, and probably others that are escaping me at the moment...
My go-to machine has always been the 312-A. It could use a couple extra horsepower (your 314-H would be good) to run the 2 stage blower (minimum HP I'd be comfortable running with) and the 48" deck with powerflow bagger.
My ideal machine would have been a 520-H, due to gear reduction steering, heavy duty front end, and ability to take a 60" deck. But I bought and sold a lot of them and wasn't smart enough to keep one. I don't have as much for a GT any more now with a lot of acreage, but I'll always keep my 312-A with its original accessories for sentimental reasons.
thanks guy, this is what I was wanting to hear. It's about what I thought but wanted to hear from somebody who'd been there.
On the hydro units, is the rear axle heavy cast iron like the -8 units ? And do the hydro have hi/lo range
On the hydro units, is the rear axle heavy cast iron like the -8 units ? And do the hydro have hi/lo range
The hydros do not have hi-low. However they do share a similar rear end.thanks guy, this is what I was wanting to hear. It's about what I thought but wanted to hear from somebody who'd been there.
On the hydro units, is the rear axle heavy cast iron like the -8 units ? And do the hydro have hi/lo range
1 - 13 of 13 Posts
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