Abstract: A disc type refiner, for paper pulp processing and the like, is provided with an automatic control mechanism to prevent contact-clashing of the refiner plates on short term losses of feed and to sense the long term losses of feed so as to open the refiner plates before contact-clashing occurs. The control mechanism includes a counter-force-producing means acting in opposition to the refining or attrition force-producing means such that, on either short or long term loss of feed, resistance to plate clashing is provided. Moreover, the counter-force-producing means is monitored and the monitor provides signals to actuate, in cooperation with other control devices, a desired sequence of operative steps to effectuate either the continuation or the discontinuation of the refining operation.