As a gearbox functions, it can generate different amounts of heat due to different factors such as ambient external temperature, load, duration of operation, internal friction, gear drive type and other factors. It’s important to monitor the thermal limits of your gearbox – too much heat can lead to failure of the power transmission, which can require a costly gearbox repair. Therefore, understanding the thermal limits and cooling options are important for any industrial maintenance technician.
Heat Generation
Each gearbox has a thermal rating that is based on the maximum power it can transmit continuously without surpassing a determined oil temperature. Use the thermal rating to match the correct gear box with the continuous operational power the gearbox will have to endure. This will keep the gearbox under its thermal limit, which allows it to function without a decreased service life.
It’s also important to make sure you have the correct parts installed. Incorrect sizing of equipment to the required power can lead to excessive heat generation from the increased friction on the internal components. This excessive heat can detrimentally affect the oil’s ability to adequately lubricate the gear box, causing premature failure and gearbox repair. Use different cooling options and maintenance techniques to regulate the oil sump temperature, which will maintain the gearbox operating temperature.
Basic Cooling Options
To keep the gearbox under the predetermined thermal limit, you can utilize a variety of methods ranging from air-cooling the case with fans all the way to complex water or oil cooling systems. The simplest form of air cooling is a shaft-mounted fan on the gearbox. This will move air around the case of the gearbox, removing heat with convection. If more cooling is required, you can also utilize an electric fan to move air across the gearbox in larger volumes to dissipate a larger amount of heat.
A more complex method of cooling is an air-to-oil cooler. This method for cooling a gear box uses a pump to move oil through a coil or radiator. The coil or radiator would cool the oil using a fan to rotate air. This method increases cooling capacity to help keep the gearbox under the thermal limit.
Posted under Machinery Maintenance on Thursday, March 3rd, 2011