Tips: How to Inspect, Maintain, Service, and Repair Gear Reducers on Extruders

In extruder maintenance, the most crucial component to maintain is, of course, the gearbox, as it is highly valuable and has a long lead time. The procedures and steps for its maintenance are much more detailed. Today, this article summarizes some key points of daily inspection, maintenance, and servicing of the gearbox from several different aspects. Let’s take a look together!

Daily/Weekly Monitoring:

- Oil level ("middle of the sight glass" applies only when the gearbox is not running)

- Oil temperature (should be below 65-70°C)

- Filter pressure drop (typically <2 bar)

Vibration/Noise

Leakage

I. Maintenance of the Gear Reducer

The gear reducer area should be well-ventilated, and the working environment temperature should be within the range of 5℃-35℃.

② Frequently check the oil level of the gear lubricant in the box to ensure that all transmission components inside have good lubrication.

③  Pay close attention to regularly checking the bearing positions of the box. During operation, the temperature variation should not exceed 45℃.

After being put into use, the new gear reducer should have its internal oil cleaned and the lubricant replaced after 500 hours of operation.

⑤ The gear reducer box must undergo regular maintenance and inspection once a year, with the following work content:

a. Open the gear reducer cover and inspect the wear and meshing condition of each transmission reduction gear working surface. If there are burrs or shallow pitting on the meshing surfaces, use an oilstone to smooth them out. For gears with significant wear, conduct mapping and prepare to manufacture spare parts for replacement during the next maintenance.

b. Check the wear condition of each bearing. First, clean the bearings thoroughly and inspect the inner and outer races for any cracks; observe the noise level during no-load operation and measure the radial clearance. If no issues are found, add some grease and continue using them.

Check if the lubricating oil in the box is clean. If there are many impurities or metal powders mixed in the oil, filter out the impurities from the lubricating oil, and then replenish the oil to the required level.

After cleaning and inspecting the parts inside the box, install the box cover; after adding sufficient grease to each bearing position, replace with a new oil seal and tighten the bearing cover.

e. Clean the exterior of the gearbox to keep the equipment clean.

2. Principles for Replacing Parts Inside the Gearbox

If deep wear pits appear on the involute meshing tooth surfaces of the gear, and the gear produces loud and irregular noise during operation, often accompanied by impact and vibration,This gear should be replaced.

2. The inner or outer ring of the ball bearing has cracks; the ball cage is damaged; there is a large radial clearance between the inner and outer rings; there is significant noise when the bearing is rotated by the outer ring, etc. After cleaning the rolling bearing,If any of the above-mentioned damages are found, the rolling bearing should be replaced.

3. Precautions for Gear and Bearing Replacement and Installation

① Gears and bearings should be cleaned before installation and deburred.

② Inspect and replace the gear hole, assembly shaft, key, and keyway dimensions to meet the fit tolerance requirements specified in the drawing; the replaced rolling bearing should be of the same model as the original bearing.

The gear hole and shaft should be fitted with an H7/k6 or H7/r6 fit.

④ The outer ring of the rolling bearing and the housing adopt a k7/n6 fit, and the hole and shaft adopt an H7/m6 or H7/k6 fit.