electrical connections to the linear transducers the wire terminals were soldered to a connector mounted on the dust cover which required difficult assembly and disassembly of the solder connections during replacement of the transducer while the dust covers provided the desired protection from the ambient environment replacement of the transducers due to damage wear or inoperability was time consuming due to the need to first remove the dust cover and then disconnect each soldered electrical connection the use of the plug in connector enables all the connections to be made or disengaged at one time in a quick and easy plug in action referring now to fig4 and 5 there is depicted the spindle 80 according to the present invention the spindle utilizes a rotary actuator 82 such as a parker m series rotary actuator model no 150m 1803c xxiv b63 this rotary actuator 82 utilizes two spaced parallel rotatable racks 84 and 86 having a rotatable pinion 88 therebetween simultaneous activation of the racks 84 and 86 causes opposite linear movement of the racks 84 and 86 and a rotation of the pinion 88 as shown in fig5 the pinion 88 is connected to one end of an elongated shaft 90 which is rotatably mounted by means of a first bearing assembly 92 at one end and a second bearing assembly 94 at an opposite end of a housing 96 which is fixedly mounted on the platen 36 the second bearing assembly 94 is preferably a conventional ball bearing assembly which supports one end of the shaft 90 the first bearing assembly 92 is improved over assignee 39 s prior casting rollover apparatus in that it includes a unique arrangement of thrust bearings which are mountable in the housing 96 in a simplified assembly.