Dc motor controller in use after a period of time, you need to repair, this is in order to better use of equipment. The overhaul of cylinder is very important, especially some of the details. The following people and small make up to look at how to repair. 1. To dc motor controller cylinder roundness and cylindricity measurement, depending on the degree of wear and tear it to determine whether the boring cylinder replacement. 2. Check the roundness and cylindricity cylinder and conform to the relevant provisions. 3. Of dc motor controller to check inside the cylinder surface, surface, no crack, sand holes, scars, defects such as scab. 4. Require it to the cylinder water jacket defects such as cracks or leaks cannot happen. 5. Requirements of the dc motor controller cylinder diameter does not allow more than 2% of the original size, and cylinder wall thinning doesn't allow more than 1/12 of the original wall thickness. Only do these, can better use of dc motor controller.