42B Lot 20 thru Lot 22 Head Assembly Tips

Spindle Sleeve Installation and Head Service Notes

Spindle Sleeve Installation Tip 1:

The installation of the Spindle Sleeve into the headstock of this range of serial numbers is complicated by the use of (2) 'light-duty' Timken tapered roller bearings to provide support to the rear end of the spindle sleeve.

The problem stems from the fact that these bearings are relatively narrow in comparison to their diameters and tend to 'cock' when passed over the bearing journals. Normally, this is not a problem in most applications and requires only some light 'tapping' to get the bearings to pass down the shaft.

In the Lot 20 thru Lot 22 machines, however, the bearings are situated between two closely spaced casting walls of the head and there is NO access to permit 'tapping' the bearing cones.

The method used in the Lucas shops - when the machine was originally manufactured - was to stand the Spindle Sleeve vertically on the shop floor and to lower the head casting slowly over the upright Spindle Sleeve. The natural tendency of the bearing cones to 'self center' in the previously mounted bearing cups affords the best opportunity to assemble the head with a minimum of difficulty.

Spindle Sleeve Installation Tip 2:

A simple ring nut with a setscrew is used to apply preload to the 'light-duty' Timken bearing set. It is IMPERATIVE that you do not allow the Spindle Sleeve to rotate with the setscrew protruding above the surface of the ring!

While there appears to be adequate clearance 'on top' to prevent the setscrew from hitting the casting - there is almost NO clearance between the OD of the bearing locking ring and the 'floor' and 'rear wall' of the head casting. If you rotate the Spindle Sleeve, it is extremely easy to get the tip of a protruding setscrew to 'wedge' to the head casting and there is no good method available to free it and allow it to rotate back to the access slot.  If you have this happen, the only positive way to correct the problem is to remove the Spindle Sleeve from the head casting and start re-assembly from the beginning.

High-Range Clutch Area Service Tips:

42B Lot 20 thru Lot 22 machines used a mechanical 'dog clutch' for the high-speed range in the head. The clutch is operated by an air cylinder.  The cylinder rod is threaded directly into the end of a shaft that slides the shifter shoe that is - in turn - engaged into the sliding portion of the 'dog clutch'. Several minor modifications should be done to the head casting when this area of the machine is worked on to permit easier maintenance.
 

1. The shifter shoe is secured to the sliding shaft by a tapered pin. The large end of the pin is on top and cannot be removed without nearly complete disassembly of the head gearing due to interference with the head casting. We recommend that an access hole be drilled vertically into the top of the head casting directly above this taper pin so that it can be removed - when occasion requires - without the need to remove the head gearing.
   
   
   The hole should be fitted with a simple plug to prevent trash and swarf from entering the head. We have dimensional information available to permit locating the correct position for the hole prior to head disassembly.
   
    
2. The threaded connection between the shifting cylinder and the sliding rod is secured with a crosswise setscrew to lock the threads. The setscrew enters the shaft from the 'column aside' of the shaft and must be accessed 'blind' by inserting your arm into the slow motion cavity and around the corner and locating it by 'feel alone.
   
    

We recommend that a circular access hole be bored into the 'operators-side' face of the head and that the shaft be re-drilled to position the setscrew to the 'front'. The casting hole should be plugged with either a fitted plug or a simple sheet metal shield to prevent trash and swarf from entering the head. We have dimensional information available to permit locating the correct position for the hole prior to head disassembly.

Without the front access hole, a damaged setscrew socket or 'bugged' threads on the cylinder rod can make this assembly nearly impossible to service without almost complete disassembly of the head.