Shumar Double Roll Crusher

- All Shumar crushers have two machined rolls to which the crushers segments are bolted.
- Each roll is fitted with six crusher segments.
- Mn. steel segments are used in primary and secondary applications, while white iron is used for some secondary washed coal applications. All segments are hand ground for proper seating.
- One roll is fixed while the loose roll is spring-loaded to enable foreign matter to pass throught the crusher without causing damage. The loose roll position can also be adjusted for various product output sizes via two adjusting spindles.
- The loose roll bearings slide on the main frame and are guided at the bottom by a wearing strip fixed to the main frame and at the top by a separate top guide frame.
- Phosphor bronze and steel wearing strips are provided for all the sliding surfaces.
- The bearing are spherical roller bearings. To protect seals, the loose bearing housings are designed to pivot in the event of the roll kicking out.
- The hood is a permanent part of the frame. The outlet shoot is fitted to this section of the hood. The crusher is thus totally sealed.
- The crusher is supplied with a V-pulley drive, guard and drive stand with a pair of geared motors driving each roll separately. The drives are both situated on the same side of the machine to make it more compact.
- The segments fitted to each crusher are carefully chosen to suit the customers needs. Special segments are designed if stock segments are not suitable.

1. Never crush coal that is already product size. Screen out undersize before crushing. Each time sized coal goes through a crusher, fines are produced, even if the incoming coal is smaller than the crusher setting. This is valid even when primary crushing.

2. Choose the right type of crusher. Double roll crushers have proved themselves to be the most effecient type of machines in the coal industry.

3. Use the correct crushing ratio. Crushing ratio is defined as the ratio of input size to output size. The ideal ratio is
2 : 1.3 : 1 is possble but anything above that ratio causes a serious decrease in crushing effeciency.

4. Use a crusher with th right roll diameter with respect to the desired input and output size. Large pieces of coal fed to small diameter rolls produce a rolling effect of the coal as the teeth battles to grip the coal, thereby reducing throughput tonnage and increasing fines and segment wear. The nip angle, the angle from the horizontal where the rolls grip the coal, must always be as small as possible. Reduce the crushing ratio nip if the angle is too large or use larger diameter rolls. 

5. One fo the most important aspects of the crusher design is the correct segment tooth profile. Let your crusher manufacturer know what product you desire and we will give you the correct profiles. If your product changes, contact us and we will advise you wether your present profile can still be used or if the profile should be changed. Power consumption is very largely influenced by the correct selection of the tooth profile.  

6. The roll speed is also important. Always contact your crusher manufacturer before altering the roll speed with respect to the imput size and crushing ratio. Too high a speed can result in slippage with a resultant increase in fines and segment wear.

7. When doing cost cutting exercises, do not try and reduce capital outlay on your crushing curcuit to the detriment of the crushing effeciency. The capital you save initially will be lost later on a continuous basis as you create extra fines and lower profit products.