13 Dec 2021

The importance of oil filtration in Hydrostatic Transmission

Hydrostatic Transmission Filter

The post of this month is dedicated to the hydraulic filtration in hydrostatic transmission.

The hydrostatic transmission is a system that generates and transmits power to perform a job through the pressurisation and release of a fluid. In particular, the energy captured by the fluid through the hydraulic pumps is transferred to the transmission of a vehicle. This type of transmission can be used to power different types of machinery, although it is more commonly used in heavy vehicles, such as tractors and backhoe loaders. The main advantage of the hydraulic transmission is the transmission of great power at any distance.

What does hydrostatic transmission filter do?

The filter is a key part of the transmission system, designed to prevent metal shavings from the gears, and other dirt and debris, from contaminating the transmission fluid. The transmission filter also removes the shavings deriving from the general wear of the machine.

It sits between the transmission pan (that collects excess fluid) and the tube that regulates the transmission fluid pressure.

Today’s modern transmissions and their advanced technological design depend on near-perfect lubrication to function, therefore a high quality hydraulic filtration in hydrostatic transmission is required to ensure:

  • proper filtration of oil before it’s delivered to the transmission
  • reliable performance of the lubricating system

The hydrostatic transmission filter ensures the required cleaning class of the oil and provides protection to the sensitive transmission components. The proper transmission filters keeps vehicles running smoothly.

The filter layout, filtering media and housing material are important key factors in establishing the quality of the transmission filter.

The status of the art of hydrostatic transmission filters layout

combined suction-return filter
FTA-FTB Series

In machines with a hydrostatic drive and combined working hydraulic system, combined return-suction filters replace the suction or pressure filters previously required for the feed pump of the closed-loop hydrostatic drive circuit as well as the return filter for the open-loop working hydraulic circuit.

The hydrostatic transmission filters are designed to work in hydraulic systems combined with hydrostatic transmission, when the return flow is higher than the flow of the boost pump in any operating condition (>50% in normal operating conditions). The oil from the return line of the system is filtered from the inside to the outside of the filter element and goes to the suction of the boost pump with a 0,5 bar pressurisation. The exceeding flow rate goes into the reservoir.

The functions of this transmission filter configuration are:

  • to supplement inline filtration, such as return line and pressure line filters, in conditioning and cleaning the reservoir
  • to extend the service life of system components, in-line filters, and oil
  • to reduce fine contamination, oil aging, and down time of machines
  • to serve as flushing unit for new systems and machine break-ins

Main advantages of hydrostatic transmission filters

 The main advantages of the combined suction-return filter layout, like FTA-FTB series manufactured by UFI Filters Hydraulics, are:

  • Only one filter for both circuits
  • The total oil volume filtered in the return line
  • Excellent cold start
  • Pump always fed with filtered oil

Other transmission filters layout

FPG Series

For some specific applications, where there is not enough room to mount the filter on the tank, an in-line version is required. For these hydraulic systems, UFI Filters Hydraulics has studied some specific filtration solution, as FPH or FPG series.

All UFI Hydraulics’ hydrostatic transmission filters are specially engineered to protect the transmission system in rigorous conditions, thus providing a reliable solution for several applications, from agricultural and construction machines to heavy-duty applications. Moreover, UFI Hydraulics transmission filters can rely on the technology of FormulaUFI.Micron, based on inorganic fiber impregnated with resins, having such characteristics of first class filtration efficiency and low differential pressure drop over the whole lifetime of the element, available in 5, 7, 12, 16 and 21 µm(c).

Discover the complete UFI Hydraulics range or select the best solution for your application by using one of our webtools.