I am really trying to understand how the hydrostatic transmission in my tractor works. I have read the WSM on how the various operating modes work but it assumes you know the terminology and what the various parts are/do. Is there a site somewhere in the internet world where I can learn all of this?
HST For Dummies
- Thread starter imarobot
- Start date
ken erickson
Well-known member
Equipment
B7100 hst, 2650 front mount snowblower, L2501 hst qa loader
North Idaho Wolfman
Moderator
Staff member
Lifetime Member
Equipment
L3450DT-GST, Woods FEL, B7100 HSD, FEL, 60" SB, 743 Bobcat with V2203, and more
︎ to go forwards
︎ to go backwards
jyoutz
Well-known member
Equipment
MX6000 HST open station, FEL, 6’ cutter, forks, 8’ rear blade, 7’ cultivator
Watch the youtube videos then ill add this. 2 cylinders with pistons in them. The pump cylinder does nothing while in neutral. When you push the pedal forward or reverse the swashplate moves one direction or the other (forward or reverse) thus pushing the pistons in. This now is creating pressure which goes out one direction or the other depending on angle to the motor which has a fixed angle swash plate and depending one which direction the flow is coming forces the cylinder to turn which turns shaft connected to transmission. Maybe this helps some
bbxlr8
Well-known member
Equipment
L2501 w/R14s, LA525, BH77, SGC0660, CL 5' BB, CL PHD, WG24 + Ford 1210 60" mmm,
Another counterintuitive thing about HST is getting more power by backing off a bit instead of pushing more under slowdown with extended load. Example - full bucket going up a hill etc.
Right, more pedal is like a higher gear, less pedal is like a lower gear.
Forget about gear drive - power transfer, completely. Think liquid.
To overly simplify:
It's liquid pressure. Imagine two hoses connected to 2 hose bibs on your house. We'll call one hose forward, and the other reverse. You open the hose valve on 'forward' and pressure comes out of the hose and drives the machine forward. The more you open the valve, the more pressure comes out, increasing the speed. Reverse works the same way. BUT it is an enclosed system so while 'forward' is pushing fluid, reverse is sucking fluid. And vice versa. (Not like 2 water hoses on your house). There is little or no delay in forward to reverse changes because it is liquid pressure, not metal gears.
The engine drives a fluid pump in the transmission. The forward and reverse operator pedals switch the fluid flow direction into a fluid drive. The fluid drive drives the wheels. Neutral or a centered pedal drives nothing in the fluid drive. It just recirculates.
All you are changing is the fluids direction by operating the treadle pedal. The fluid is always under pressure via the fluid pump as long as the engine is running and 'in gear'.
Simplified.
I hope that helps.
To overly simplify:
It's liquid pressure. Imagine two hoses connected to 2 hose bibs on your house. We'll call one hose forward, and the other reverse. You open the hose valve on 'forward' and pressure comes out of the hose and drives the machine forward. The more you open the valve, the more pressure comes out, increasing the speed. Reverse works the same way. BUT it is an enclosed system so while 'forward' is pushing fluid, reverse is sucking fluid. And vice versa. (Not like 2 water hoses on your house). There is little or no delay in forward to reverse changes because it is liquid pressure, not metal gears.
The engine drives a fluid pump in the transmission. The forward and reverse operator pedals switch the fluid flow direction into a fluid drive. The fluid drive drives the wheels. Neutral or a centered pedal drives nothing in the fluid drive. It just recirculates.
All you are changing is the fluids direction by operating the treadle pedal. The fluid is always under pressure via the fluid pump as long as the engine is running and 'in gear'.
Simplified.
I hope that helps.
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Thank you everyone for your inputs. I understand the basics of hydrostatic drive and am working at learning the details. I've read the descriptions of the various modes in the WSM and am trying to get a better understanding of details of all the individual components, what they do, and how they work. I'm also trying to learn the schematic diagrams of the hydraulic system to be able to identify all the components are.
I'm getting there, thanks to all your inputs and the videos.
This all started when I tried to figure out why I'm having an issue with Stall Guard. If I select it with the HST switch the Stall Guard light does not light up on the display. Not sure if it's just the display light or something more.
I'm getting there, thanks to all your inputs and the videos.
This all started when I tried to figure out why I'm having an issue with Stall Guard. If I select it with the HST switch the Stall Guard light does not light up on the display. Not sure if it's just the display light or something more.
I always let the tractor warm up until I see one block of the temperature gauge displayed before doing anything.In cold weather it does take quite a while. As the dealer I bought the tractor from told me, go out and start the tractor, go back in the house and have breakfast and a second cup of coffee, then go back out and wait a half hour for tractor to warm up.
It is my understanding that Stall Guard is to prevent too high of a load on the tractor within it's operators use and settings. Including throttle setting.
Too high of a load can mean operating implements at too low a throttle setting Or at idle speed.
Load in this context is not carrying or lifting capacity, but it is engine speed vs power and torque requirement.
Remember, diesel engines like to rev. They Need to rev. Read your owners manual and operate it a lot to learn your tractors rev needs. You don't want to redline it but you do want it screaming pretty good under load. Read the owners manual or have the dealer's rep come by and teach you. Or talk to an experienced neighbor. Lugging a diesel is Never good. Give it the gas.
(Don't do this unless under load with a rear PTO implement attached): Set your dash tachometer to display rear PTO. Rear PTO should be 540. When using rear PTO, see how high you have to throttle it up to get to 540 RPM. It's screaming. That is no accident. That is designed into your machine by necessity. Rev it up. But don't get crazy.
Never lug a diesel. If you are even turning the front wheels or raising the loader, give it a bit of throttle. If you don't know what lugging is, Please learn. Lift the loader at idle, the engine sounds like it is struggling... that is lug.
I don't mean to assume too much, so if you know all of this; I post it respectfully. And Disregard.
Too high of a load can mean operating implements at too low a throttle setting Or at idle speed.
Load in this context is not carrying or lifting capacity, but it is engine speed vs power and torque requirement.
Remember, diesel engines like to rev. They Need to rev. Read your owners manual and operate it a lot to learn your tractors rev needs. You don't want to redline it but you do want it screaming pretty good under load. Read the owners manual or have the dealer's rep come by and teach you. Or talk to an experienced neighbor. Lugging a diesel is Never good. Give it the gas.
(Don't do this unless under load with a rear PTO implement attached): Set your dash tachometer to display rear PTO. Rear PTO should be 540. When using rear PTO, see how high you have to throttle it up to get to 540 RPM. It's screaming. That is no accident. That is designed into your machine by necessity. Rev it up. But don't get crazy.
Never lug a diesel. If you are even turning the front wheels or raising the loader, give it a bit of throttle. If you don't know what lugging is, Please learn. Lift the loader at idle, the engine sounds like it is struggling... that is lug.
I don't mean to assume too much, so if you know all of this; I post it respectfully. And Disregard.
Last edited:
North Idaho Wolfman
Moderator
Staff member
Lifetime Member
Equipment
L3450DT-GST, Woods FEL, B7100 HSD, FEL, 60" SB, 743 Bobcat with V2203, and more
Reading the WSM should answer this question!
In cold weather it does take quite a while. As the dealer I bought the tractor from told me, go out and start the tractor, go back in the house and have breakfast and a second cup of coffee, then go back out and wait a half hour for tractor to warm up.