11 important tips on how to ensure a long lifetime on your Haarup Mixer

1. Do not start/stop with a full load.

The mixer is not designed for repeated start and stop with a full load.

If it is not possible to discharge the mixer (for any given reason) even though the concrete is ready then do not stop the mixer and later restart when it is possible to discharge the concrete. Instead use a frequency regulator (do not go below 30 Hz) to reduce the mixer speed, to prevent the concrete from being “over-mixed” during the waiting time.

Do not stop the mixer to open the cover lids in order to inspect the concrete. If it is necessary to inspect the concrete Haarup can offer a concrete sample door which makes it possible to take a sample while the mixer is running.

2. Avoid overfilling and overloading the mixer.

Know the maximum the capacity of your mixer. Always observe the limits for volume and weight of the filled materials, regardless of which limit is reached first. 

3. Grease the seals.

Remember to lubricate the mixing gear seals as well as the output shafts on a regular basis with water resistant grease of type Almatek 1233, as described in the manual. If the seals are not greased, water and dirt will eventually penetrate into the gear and the gearbox causing increased wear.

Almatek 1233 is available from Haarup or other leading suppliers of lubricants. 

4. Do not direct high pressure water at the seals.

Make sure to never aim high pressure water directly on the seals of the gear box. The water can eventually wash the sealing grease away from the seals and water might then penetrate into the gearbox.

5. Clean the discharge doors.

If the production is paused for a longer time period (at the end of the day, before the weekend, etc.) leave the discharge doors open. Remember to clean the discharge doors. Oil or lubricate after the discharge doors are cleaned. A properly lubricated and cleaned discharge door can be opened and closed by hand, if the cylinder is removed.

6. Do NOT use a hammer.

Never use a hammer on the mixer. If a hammer is used to remove concrete from the cover lids, then the cover lids get dented and bent, and the concrete will stick even more in the future. It is a vicious circle.

Dented and bent cover lids are no longer tight, and dust, water spray and even concrete splatter might escape the mixer.

7. Only use original wear parts.

Always use original wear parts. Original wear parts are engineered to ensure the longest lifetime and will also ensure the longest lifetime and durability for the mixer as well as the lowest operation costs.

8. Keep the air filter clean.

Make sure to clean or replace the small air venting filter(s) on the gearbox, so heated air from the gearbox can escape. Otherwise, in worst case, the hot air might expand and force oil through the lip seals.

9.  Vent the air around the mixer if it is operating in hot surroundings.

Make sure that the air around the mixer is ventilated to allow the excess heat from the gearbox to get away. This is especially important when the mixer is operating continuously in hot surroundings (above 30 degrees Celsius / 86 degrees Fahrenheit).

If the mixer is operating in very hot surroundings, please make sure to use synthetic gear oil. It is a more expensive oil, but it has a higher viscosity at high temperatures and this ensures a better lubrication of the bearings in the gearbox.

10. Check the oil level in the coupling between motor and gear (for 1125 liter and larger mixers).

The oil quantity in the hydraulic coupling in the gearbox has to be checked for proper oil level. Too low oil level will cause additional heat in the coupling and it will not transfer enough revolutions from the motor to the gearbox. This will cause the gearbox to rotate slower than intended, and eventually the fuse might melt.

11. Reduce the volume of tough concrete when using special aggregates.

If your recipes consist of special aggregates, steel fibers or other strengthening materials that makes the concrete tough to mix, keep in mind that these "special" mixes generate high levels of resistance in the concrete, so high that there is risk of overloading the gearbox with long-term production. In these cases, the amperage of the motor exceeds the allowable threshold.  We recommend,  when producing this kind of tough concrete reduce the volume of the concrete in the mixer, so that the amperage does not exceed the maximum, thus avoiding overloading the gear.

Written by Hans Christensen
Edited by , Haarup Maskinfabrik.