A motor replacement on a milk tank agitator has to be done in a short window between milking times; the connection type, phase and mounting direction should therefore be confirmed before the new motor arrives. Agitators are mostly driven by small, geared motors running in a vertical position.

DRG-711-4 0.25 kW 1500 rpm aluminium frame DRG three-phase motor – milk tank agitator motor

Document the existing arrangement first

  • A clear photo of the motor nameplate: power, speed, voltage, number of phases
  • Whether the motor is flange-mounted to the gearbox, and the flange and shaft dimensions
  • Whether the motor stands upright on the tank lid, and the shaft direction (down or up)
  • The agitator’s impeller type and the tank volume

The phase type is critical

On small farm tanks the agitator motor is often single-phase. DRG’s standard range is three-phase; single-phase motors are not in the range. If the farm has a three-phase supply and the tank’s control panel is suitable, a three-phase motor can be considered; however, any change to the panel and connections depends on the assessment of qualified electrical personnel. Where the panel was designed by the tank manufacturer, their opinion should be sought first.

Vertical mounting and hygiene

In vertical mounting with the shaft facing down, condensation and wash water can collect on top of the motor or on the fan cover. Stating the mounting position in the order ensures the motor is assessed for that orientation. The motor frame does not touch the milk; the impeller and shaft seal that do are the tank manufacturer’s responsibility. High-pressure water should not be aimed at the motor when the tank is washed; IP55 protection covers splashes and low-pressure water jets.

Replacement day

Compare the shaft and flange dimensions of the new motor in advance with the values on the technical drawing page, and check the agitator’s direction of rotation at the first start. Since a pause in agitation while milk is being cooled can lead to uneven cooling, doing the replacement with the tank empty is the safest route.

The topic is covered in detail on the milk cooling tank agitator motors page; low-power models can be reviewed in the list of aluminium frame motors.