Hydrostatic drive problems

A hydrostatic transmission is desirable because it causes no disruption in engine power.

hydrostatic drive problems

For all those who are wondering what is a hydrostatic transmission and how does it work, WheelZine has the answers for you. We tell you about you the benefits and drawbacks of a hydrostatic transmission, along with several other related aspects. The Honda DN motorcycle is the first consumer road vehicle that used a hydrostatic transmission.

Most modern vehicles work using an internal combustion engine. These engines produce rotational motion, but the vehicle has to move in a linear fashion.

How to Test a Hydrostatic Transaxle

IC engines have the limitation that they cannot operate below a specific rate, so this creates a problem while stopping or slowing down the vehicle. The transmission also performs this task of modifying the engine speed, by engaging and disengaging gears of different levels. Transmission can be either manual, where the driver himself has to change gears, or automatic, when the vehicle itself does this task.

Would you like to write for us? Well, we're looking for good writers who want to spread the word. Get in touch with us and we'll talk The changing of gears, either manually or automatically, creates disruptions in the power transmission of the vehicle.

This means that the engine power reduces momentarily when gears are being changed. This problem can be solved by using a continuous variable transmission CVTalso called a gearless transmission. The most famous type of CVT is the hydrostatic transmission, which finds application not only in heavy equipment, like forklifts, agricultural tractors, and industrial machinery, but also in vehicles, riding mowers, and even tanks.

When the power generated by an engine is transferred to the wheels by using pressurized fluid rather than with a drive belt or gears, then such a transmission system is called a hydrostatic transmission. In this, an IC engine drives a hydraulic pump which delivers pressurized fluid to a motor that is responsible for movement of the wheels.

A hydrostatic transmission uses the power from a prime mover, such as the crankshaft of an internal combustion engine, to operate a hydrostatic pump motor. So, the rotary motion from the engine is used to pressurize fluid, which is then directed towards a hydrostatic drive motor. To accommodate the pressurized fluid, the pistons of the drive motor have to start moving, thus creating a rotational motion which turns the wheels.

The fluid used is generally oil. The pressure and amount of fluid sent to the drive motor dictates the speed at which the wheels move. This is controlled by a swashplate, which is operated by a hand lever on the equipment. When the swashplate is vertical, no fluid is sent to the motor, and it is not operated. When the swashplate is rotated backwards when the vehicle is in motion, it has a slowing effect. The hydrostatic transmission is a closed-loop circuit, where the fluid exiting from the drive motor outlet is returned to the hydrostatic pump without being sent to the tank.

In this circuit, the input drive is the hydrostatic pump connected to the prime mover, and the output drive is the drive motor which is connected to the load. The hydraulic pump, drive motor, and other components are all enclosed in a common housing, with the motor and the pump sharing a common valve.

This enclosed assembly is then bolted to an axle. This type is compact and ideal for applications with space constraints, besides being economical. In this type, the hydraulic pump and motor are placed in separate locations, but are interconnected by high-pressure hoses or pipes.

Being more powerful, it is used in industrial applications where the required space is available. This type involves either a variable prime mover or flow-control valves, which help control the speed. Since the pump has a fixed displacement, it has to be of the appropriate size to be able to turn the motor. The output torque turning force or speed may differ from that of the prime mover, depending on what the individual displacements of the motor and pump are.

Reversibility is possible only if the prime mover can be reversed. This arrangement helps deliver a constant torque, because torque depends solely on motor displacement. Increasing the capacity of the pump will increase the speed and power. It is highly popular as a general-purpose drive, which offers a wide variety of speeds, along with an ease of control.Click here to learn more. Log in or Sign up. Sign up now! Read the timely article from Turf addressing this question. Bad boy hydro issues Discussion in ' Mechanic and Repair ' started by shakel65Jul 29, Messages: 1.

When I am on an incline, traveling on the side of incline I lose almost all power in the lever that is closest to the bottom of the incline, the mower will not keep the hill it will turn and drive down the hill. I also have issue when I am doing a lot of zero turn type of mowing. I seem to lose power on one side it varies from right to left side. If I mow wide open in a straight line the mower does fine. Thanks in advance.

Messages: 2, Sounds like your pump belt is loose. It is just one belt controlling both pumps, so it gives that feeling when it is slipping, or bouncing on the pulleys.

On the right side of the rear by the wheel you will see a long bolt going to your pump idler spring. Just tighten up the tension with the 2 nuts on it if your belt feels loose to your hand. On the extreme side, just check around for leaks on the fluid, and check your tank to make sure it is full, I have lost power on hills due to my reservoir tank being low too. If those two don't work, jack up the rear end, and work your levers while watching your lines to see if there are air bubbles in the lines, that could cause eratic behavior in driving sometimes too.

If that is the case there is a little trick to bleeding the air I can go over with you. Messages: 5. Stator was crusty not allowing the battery to charge, we cleaned the connections, seems fine now. On the 3rd time out we threw an idler pulley on the deck. How's our luck? Dude the pulley is just 20 at any mower shop, prolly cost that just for bearing Posted via Mobile Device.

I will let you know if I need one. Can you email me the bleeding trick for the hydraulic system I have the exact same thing going on with my bad boy mz, my transaxle unit is a sealed unit tho, how or what can i do to fix it. KrisndJun 13, You must log in or sign up to reply here. Share This Page Tweet. Your name or email address: Do you already have an account? No, create an account now.According to the experts at Today's Mower, there are fives types of drive gear in common use on lawn care machinery: gear, friction disk, automatic, CVT, and hydrostatic.

Hydrostatic drives are extremely easy to use when compared to geared versions; with the latter, the operator usually has to come to a complete stop and depress a clutch to change ratios, which becomes tiresome for people using such machines professionally.

Hydrostatic drives have no clutch and offer infinite speed variations.

hydrostatic drive problems

They even shift from forward to reverse with a simple change in pressure on one foot peddle. That said, there are a number of ways in which they can fail. All five drive types have certain components in common, and the failure of any of these can result in the lawnmower not moving.

Most manufacturers install a pressure-sensitive switch under the seat to interrupt the mower's self-propulsion when the seat is unoccupied; a defective switch can result in the drive not being engaged. A seized-on parking brake can either render the mower immobile or reduce its performance significantly.

All drive types must be connected at some point to the motor, so there must be a cogged or splined power take-off; stripped cogs or splines will not transmit power to the drive. Hydrostatic transmissions -- often referred to simply as hydros, hydro-drives or HSTs -- are constantly variable drives similar in operation to car automatic transmissions.

They have a pump that effects hydraulic fluid inside a closed system, and reduction gearing that responds to changes in that hydraulic pressure. Mechanical components also include a differential and a drive axle.

Fix Your Hydrostatic Transmission Problems Fast

Failure of any one of these components will prevent the lawnmower from moving. Hydraulic fluid is passed through either high-pressure rubber or metal hoses; a leak from the hoses or any of the other components will also stop the hydrostatic transmission from working. By far, the most common reason for hydrostatic transmission failure is old hydraulic fluid. John Deere states that "Operating outside of the recommended oil air temperature range may cause premature hydrostatic transmission failure.

What Makes a Hydrostatic Lawnmower Not Move?

This decay results in air and atmospheric moisture becoming blended into the oil, properly called entraining. Oil that is entrained has inferior hydraulic properties in comparison to fresh oil, resulting in less than optimal system function.

Entrained oil must be drained completely. After positioning the lawnmower to drain properly -- typically this means on a perfectly flat, level surface -- remove the drain plug and allow the machine to stand for several days until every last vestige of the old oil has dripped out. Only use replacement oil of a type recommended by the mower manufacturer. John Deere advises against using red "Type F" automatic transmission fluid and bio-based oils.

Most manufacturers recommend SAE 20W hydraulic fluid. John Cagney Nash began composing press releases and event reviews for British nightclubs in His material was first published in the "Eastern Daily Press.

In he earned an OxBridge doctorate in philosophy and immediately emigrated to America. By John Cagney Nash. Hunker may earn compensation through affiliate links in this story. Hydrostatic transmissions are common on ride-on lawn care equipment.Husqvarna riding lawn mowers have a sealed transaxle or transmission and do not require fluid monitoring. When you purchase a new Husqvarna riding lawn mower or have a new transmission installed, however, purge the transmission to release air within the system.

Air enters the system during shipping and when the transmission is replaced. Air in the system affects the supply of power to the lawn mower's wheels for forward and reverse movement.

Raise the Husqvarna lawn mower's attachment lift lever on the left side of the operator's seat to the highest position. Walk to the rear of the lawn mower, and pull the freewheel control outward and down, locking the transmission in the disengaged position. Push the lawn mower to a flat, open area of your lawn. Sit in the operator's seat. Press the brake pedal forward with your left foot to engage the brake, and hold the brake pedal in that position.

Push in the attachment clutch switch on the right side of the dash to disengage the cutting blades. Push the throttle control on the left side of the dash upward to the fast setting, and pull out the choke below it to engage it. Insert and turn the ignition key to the right, and immediately release it when the engine starts. Push the throttle control down to the slow position. Place the motion control lever on the right side of the seat in the center, neutral position.

Move the motion control lever upward to "Forward" for five seconds. Move the motion control lever down to "Reverse," and hold it there for five seconds. Repeat this procedure an additional three times. Move the motion control lever to the middle, neutral position, and turn off the engine by turning the ignition key. Walk to the rear of the lawn mower.

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Lift the freewheel control, and push it inward to engage the transmission.I am having problems with the forward speed, it barely moves. I replaced the drive belt and made all the recommended clutch adjustments. Any suggestions? They have a service kit out the dealers will deny it but Murry told me about it that will allow you to drain and refill the hydraulic fluid.

I have a similar problem but if you have used the tractor hard like I havethe drive is probably worn out. There are no repair parts.

hydrostatic drive problems

I'm looking for a VST o24b peerless transaxle. Know where I can find one? Jack what model do you have? Harold Jensen Model x6B Telinsme Just a note; simple, but sometimes overlooked: Make sure the clutch pedal is all the way back to its original position. Rds, Telinsme Jerry Regis I am having the same problem with my murray tractor.

I would like to know if anyone was able to help you. It's a great tractor other than this transmision problem. I reassembled it but half dozen parts missing so I'm looking for a used unit for parts. Chris mentioned an upgrade--what is the model number? Tim I have a honda lawn mower with hydrostatic drive problem similar to many described in this forum.

It starts out finebut gradually looses forard drive until I go to maximum setting just to move across the lawn. Shut down for a few minutes and it will go again for a while. You must include your email address above to receive this notification. Rear View Backup Camera. Engines Misc. How much is your farm tractor worth? Find resale prices for tractors built from through today, with complete specifications and serial numbers.

Harold Jensen. I have a Murray Riding lawn mower with hydrostatic drive. Kenny Rex.I have an YTH It was losing power from the transmission, not the motor to the point that it would not climb a hill. I put on a new belt and got a tranny from a neighbors mower that I know is good and is the same stock Tuff Torq K The replacement was exactly the same with the same dimensions, mounting points and pulley. My mower now goes about half the speed as new.

The belt is routed correctly, the new belt is the correct number and is stamped on the side. The new belt is not Husqvarna, but is listed as an OEM replacement.

The tensioner spring is pulling the pulley all the way back, I can push the pulley no more than a couple of millimeters further than the spring is pulling it. The belt does seem too loose, I don't know how much slack should be in it, but there's a good 1 inch to 1 and half inch of play on the long section without the tensioner. What am I missing? Follow the rod connecting the forward pedal back to the transmission.

Too much in one direction gave tremendous forward speed, and little to no reverse speed. Too much in the other direction gave me neck whipping reverse, and NO forward at all. This might be something you can look into. What transaxle does it have? There will be a sticker under the seat with either hydro-gear or tuff torq on it. Its more than likely the linkage Husqvarna doesn't put adjustments on their tractors to save money.

There is just too much variation in the hydrostatic transmission and the husqvarna chassis to make "one size fits all" control rod. I've heard some just run slower than others Get slow and quit Yadda yadda. Sometimes this can occur if pivoting locations with pins have become elongated from vibration wearing of the pivot parts.

And sometimes Also, if this is the first use this season and the unit was stored in the free wheel mode, refer to your owner's manual to the "purge trans" procedure. Long term storage in free wheel mode sometimes allows the hydro oil to drain out of the pump and motor sections inside the trans.

If you fail to perform a purge trans procedure before using after long term storage, the air in the pump and motor will prevent operation of the trans. If it seems there is nothing wrong with the linkage, check to make certain the trans belt has not jumped off or broken and if all that is good, do a purge of trans. The replacement was exactly the same with the same My problem turned out to be the brake.

When engaged, relieves the tension on the drive belt. When released, full tension was not being applied. I checked this by putting the mower in motion with little power evident and then reaching forward with my heel to pull back on the brake pedal.

The thing took off. Did an examination of the brake's operation from front to rear and couldn't see any obvious problems. Cleaned everything that touched the brake linkage, shot a little WD40 anywhere any parts moved, and called it fixed. That is what happened on mine too. Mine is the YTH18K I used my foot to pull back on the brake when going up a hill and my mower climbed right up.Your final drive or hydraulic motor represents a major investment in your equipment — not just because of the cost, but because failure literally brings your equipment to a grinding halt.

In this Shop Talk blog post, we are going to discuss how you can solve the biggest problems with hydraulic motors and keep your equipment running. As it clogs, pressure will build because hydraulic fluid can no longer freely pass through the case drain line. Pressure will continue to build, eventually forcing hydraulic fluid into the gear hub, blowing seals, piston shoes, and bearings along the way. If it keeps building up unchecked, it can even crack the cover plate or blow it clean off.

The most catastrophic final drive failures that come into our shop can often be traced back to the case drain filter. Another key way to keep your final drive in top shape is to regularly check and change the gear oil. Gear oil is key to minimizing friction between contact parts and conducting heat away.

Checking the gear oil levels regularly allows you to detect leaks as soon as they happen. Also remember to follow manufacturer guidelines on what oil to use — your hydraulic motor or final drive was designed with that oil in mind.

Leaks are a big deal for final drives because they not only allow important fluids to leak out but allow contaminants to find their way in. Imagine those expensive, high-performance bearings getting filled with abrasive sand or those precision-lapped surfaces getting scoured with plain old dirt.

One of the best ways to protect the investment you have in your final drive is to fix leaks as soon as they are discovered. Investing a little time and money in preventative maintenance will go a long way in keeping your equipment running for as long as possible. Main Menu Home. About Us. Why Buy From Us. Identifying Final Drives. Our Rebuilt Pumps. Shop Talk Blog. Core Buyback Program. Contact Us.

Here’s Your Complete Guide to Hydrostatic Transmission

Shop All. Shop Spare Parts. Hydraulic Drive Motor Problems? Check the Gear Oil Levels Another key way to keep your final drive in top shape is to regularly check and change the gear oil. Fix Leaks Leaks are a big deal for final drives because they not only allow important fluids to leak out but allow contaminants to find their way in.

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