GB814701A - Differential drive apparatus - Google Patents

Abstract

814,701. Drive of paper-making machines. BLACK-CLAWSON CO. Sept. 17, 1957 [Sept. 17, 1956], No. 29239/57. Class 96. [Also in Group XXIV] The shaft 80 of the calender or drier section of a paper-making machine is maintained at a constant speed differential with respect to a main driving shaft 15 of the machine by means of an epicyclic train comprising a driving sun 60 adapted to be coupled to the shaft 15 through bevel gearing 30, 32, pneumatically operated clutch 40, 42 and shaft 50, a driven sun 77 on shaft 80 and planets 67, 68 carried by a cage 72. The cage 72 is adapted to be driven in either direction by a reversible hydraulic motor 85 to vary the speed differential required by variation of the output of a reversible displacement pump which may be separately driven or driven off the main shaft 15. Changes in the speed differential between shafts 15 and 80 is sensed by changes in pressure between a tachometer pump 95 geared to shaft 15 and a feedback tachometer motor 90 driven thereby and geared to the cage 72. Such changes act to regulate the output of the pump supplying motor 85 so that the cage is driven faster or slower to compensate for any speed changes. The output of the tachometer pump 95 is variable by a control 97 operated by a reversible electric motor 98 to provide a variable reference pressure corresponding to the desired speed differential required between shafts 15 and 80. The gearing maintains the speed differential of a section over a main drive shaft and/or over an adjacent section to provide the necessary " draw " which can be regulated by adjustment of the tachometer pump 95. Also, slack in the web, following a breakage therein, for example, can be quickly taken up by operating a valve shortcircuiting the pump 95 to drop the output pressure thereof and thereby increase the output to pump 85 to drive the cage 72 at an increased speed until the slack is taken up. The gearing may also be utilized for " inching " forwards or in reverse by releasing the clutch 40, 42, applying a pneumatic brake 53, 55 to the shaft 50 and sun 60 and operating valves to supply pressure fluid in one direction or the other to motor 85 to drive the cage 72 and shaft 80 at a slow speed.