What is a Hydrostatic Lawnmower?

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When you are looking for a new lawnmower, you can be overwhelmed by the large variety of models. Self-driving, push mowers, sit-on lawn mowers, zero-turn mowers, gas mowers, electric mowers, and many more. While there are many varieties available in the market, lawnmowers can be classified into three most common types: manual, automatic, and hydrostatic.

The most powerful is hydrostatic. As the term “Hydro” depicts “fluid” and “static” shows “motion,” it refers to the empowerment of the wheels. Therefore, a hydrostatic drive indicates a “fluid drive” similar to an auto transmission. A hydrostatic mower eliminates pedals and belts’ usage, thus solely relying on fluids for the transference of power from the engine to the wheels, resulting in a flawlessly smooth ride along with a lengthier transmission span.

What is a Hydrostatic Lawnmower:

A hydrostatic lawn mower is a mower that utilizes a hydrostatic transmission instead of belts and gears commonly found in other lawnmowers. The hydrostatic system contains a hydraulic pump and motor and uses a sort of oil to transfer the power from the main engine to other parts of the machine like the wheels and blades. The advantage is that the lawnmower has superior performance, no gears, and can operate at a wide range of speeds. The disadvantage is that it is an expensive system that is less efficient and requires more maintenance.

What is a Hydrostatic Lawnmower? 1
(CC BY 2.0) by Combsy

To get a better understanding of the pros and cons of a hydrostatic lawnmower, we will have a look at the following aspects:

  • How does a hydrostatic lawnmower work
  • The maneuverability
  • Advantages
  • Required Maintenance
  • Possible Problems
  • Hydrostatic lawnmower tips

What is a hydrostatic lawnmower in more detail

● How does a hydrostatic lawnmower work:

As stated earlier, a hydrostatic mower utilizes a hydraulics system in place of belts and gears commonly found in other lawnmowers. A hydraulic system usually refers to a system in which fluid, usually an oil of some sort, transmits the applied force from one point to another after multiplying it.

A hydraulic transmission powers this mower that consists of a hydraulic motor and a hydraulic pump. It is similar to auto transmission, just like in a car where you control the gas pedal speed. The hydraulic pump generates the pressurized flow of the oil to the hydraulic engine. Inside the engine, the pressurized oil moves the pistons, and when these pistons move, the power is transferred to the hydraulic motor. This hydraulic motor is then responsible for engaging the wheels to move. It also engages the blades of the mower into operation. Hence, liquid pressure transfers the power from the pump to the hydraulic motor, which drives the blades and the wheels, leaving no need for gears and offering a smooth mowing.

● A hydrostatic lawnmower is more Maneuverable:

Hydrostatic lawnmowers offer increased acceleration and power quickly, and there are no gears. The response time and mobility are noticeable quicker than lawnmowers using gears and belts. This gives the user full access to control the speed and direction with ease. Some of the hydrostatic lawnmowers even come with a cruise control function that allows them to set their mowing pace without the need to have your feet on the pedal.

 Available both as a riding and a walk-behind lawnmower, the hydrostatic lawnmower is usually controlled by two or one-foot pedals; however, hand levers are also offered by some models. The cruise control feature present in some mowers allows the user to remove his foot from the pedal while mowing. These mowers provide a luxurious drive with maximum comfort and a simple “press and go” function. Most hydrostatic lawnmowers are equipped with variable displacement pumps that allow the operator to maintain variable speeds. Containing a fixed amount of oil, they work on a reversible loop system (closed), making the backward and forward movement possible during the mowing.

● More Advantages of a Hydrostatic Transmission:

When it comes to lawnmower’s functioning, especially the shifting and directing, hydrostatic lawnmowers are outstanding and prove to be the best. On a hydrostatic mower, you will have complete relief from all the gear problems, especially the grinding or stuck gears due to the absence of any. It increases the comfort level and lessens the effort when the controls can change the mower’s direction while still being in motion. Many models offer hand controls for the movement, present along with the steering wheel, further simplifying the use by reducing the effort to use a brake or clutch during the mowing. Generally, a hydrostatic mower offers high power and easy maintenance of a wide range of speeds in a compact size and quick responding and granting maximum ease to the operators in changing directions even in tight spaces without any difficulty.

● Hydrostatic Lawnmower Maintenance:

A hydrostatic lawnmower requires super careful maintenance. The filters and the oil must be kept clean at all times and need to be changed after every 500 hours of use, which in most cases is once per season. The mower’s components must be cleaned and checked thoroughly for smooth working because simple hose leakages and cracked fittings can ruin the entire system. Despite this mandatory checkup, these mowers are still considered overhead and shoulders compared to other mowers because of their functions.

● Potential hydrostatic lawnmower Problems:

Even though one rarely has to face mechanical issues while using a hydrostatic model, they occasionally seem to occur. Any leakage of oil in the hydraulic pump will decrease the internal pressure and cause problems in shifting. It is noticeable in reduced power and weaker response time to the shifting than its previous performance. Any misadjustment of a transmission control arm may also affect the overall performance of the mower. It is a common indication that when the wheels continue to move, even when the mower is in a neutral state, it is time for you to inspect and adjust the adjustment bolt. When the shift control arm shows no response to your movement, you may have accidentally engaged the manual bypass lever. This lever serves the purpose of towing or push the mower, and it prevents the mower from responding when you use the control arm until you deactivate the bypass the lever.  

● Hydrostatic lawnmower Operating Error:

If you are a fresh user of these hydrostatic models, trivial operating errors may mislead you to think that you might have some gear shifting problems in some models. Before you conclude, ensure that the parking brake has been released; otherwise, the mower will fail to respond to any adjustment made by the control lever to move in a forwarding or backward direction. If your model has cruise control, do not shift the direction. Any attempt to shift may fail, which may appear like a shifting issue.

Hydrostatic Lawnmower Maintenance tips:

  • Transmission maintenance is really difficult: In most hydrostatic models, the transmissions are sealed entirely with a metal casing making it inaccessible for the user to make the repairs. It is advised that the users seek an authorized service agent for any repairs rather than repairing it themselves. The troubleshooting and the repairing of a hydrostatic lawnmower are way past the average user’s scope, especially when one lacks the appropriate knowledge, training, and tools required for the task.
  • Use gloves: While looking for any hose leaks or checking the parts, it is advisable to use safety gloves and complete other safety checks.

Related Questions:

1) What kind of oil is used in a hydrostatic transmission?

According to the manuals, the oil that goes in a hydrostatic transmission is “SAE 10w30 engine oil with API classifications of SE, CC or CD.”

2) How can a hydrostatic transmission be tested?

A simple technique to test if a hydrostatic transmission works are powering the transaxle using an electric drill and then activating the engagement lever to check if it works. This technique seems very handy, especially when one is pulling used parts unaware of their condition.

3) How can one troubleshoot a hydrostatic transmission?

If possible, null the valve. If you face overheating in the system, check the heat exchanger, inspect the tank’s oil level, pressure filters, relief valves, and look for any pump or motor case drains.

4) Can one push a hydrostatic lawnmower?

In a hydrostatic system, each wheel turns independently of the other, making it very difficult for the user to push the mower if it fails to start. However, some models come with hydraulic release making the push easy by allowing the freewheel.

5) What is the difference between an automatic and hydrostatic lawnmower?

An automatic lawnmower, as the name suggests, utilizes an auto transmission. It is a simple belt and pulley drive system with the elimination of gear changing. Only a drive pedal is used to accelerate, while another pedal functions as a brake to reduce the speed or stop the mower. On the other hand, a hydrostatic lawnmower has a gear-free system utilizing hydraulic pumps to control its speed. Like the gas pedal of an automobile, the more the pedal is pressed, the more is the velocity gained by the mower. This makes it very easy and convenient to manage.

Final Remarks:

A hydrostatic lawnmower is a lawnmower equipped with hydrostatic transmissions that allows you to mow over a wide range of speeds. This gives a smooth, comfortable mowing experience along with excellent maneuverability and response time. The disadvantage is the higher cost. But for most people, its remarkable performance and durability outweigh the higher cost.