Timing - Marchant XL

The de-rusted Marchant XL mechanism is together again (for the umpteenth time ;-) and now looks to be timed correctly. After a few tries the taking apart and re-assembling becomes easier. For the XL the interconnections between the various sub-mechanisms is unfortunately so that to e.g. change one gearing tooth, the whole drum, carriage and carriage race have to come off. And then also at least one side-wall must come off. And to remove (and replace) the carriage race the carriage-indexing rod has to be snuggled-in at the same time same as the counter-slider - these cannot be done later, it all has to come together at the same time. After dojng this a few times, it all starts to make sense and doable :)

The machine assembled without its main covers (and much cleaner than it was!):

The more interesting and tricky bits are better viewed from the back of the machine. Fortunately the large pot-metal carry-drum of the counter was relatively fine. These can swell and then foul the rest of the mechanism, so had expected to have to re-manufacture this. Fortunately this specimen is still fine, blockages were not due to this drum. Instead for example the main drum-axle was simply rusted firmly stuck inside its right-bearing - hadn't seen that before!
 

The counter carry-drum, the reversing gears, the counting-vane, the carriage interlock and of course the main-drum have one correct meshing. To get this right seemed a bit daunting, but fortunately the machine contains hints on the correct meshing.

To start with, there is one notch on the carry-drum that must line up with a vane on the direction-switch rod. It's at the very left when looking at the back of the machine:

This gets the carry-drum correctly oriented. Then the gear-train that comes off the main drum also rotates the carriage interlock. This interlock can be seen from the front; a cut-out that permits the carriage to move when the machine is at rest-position. That correctly orients the main-drum driving gear-train.

Then a tricky bit is fitting the direction reversing gear that also drives the carry-drum. It has again one (1) correct orientation. This connects the carry-drum and carriage interlock - if both are still correct after meshing this sliding gear, then it is mounted right. This gear has a few narrowed, tapered teeth to enable the sliding-over between gears - this sliding/switching will only work when things are mounted exactly right:

The little counting tooth (front) is fitted onto its rod with the vane pointing down. 

 

Another tricky bit is engaging the counting-slider rod with the carriage. Slide the carriage in to almost its left-most position and then push the slider rack to engage the transfer gear. After a few tries this usually works out - easily checked because the counting vane must smartly hit only a counting wheel gear when the carriage is in a locked position. 

The counter reversing switch and its sliding gear mechanism is very finicky - it needs the main crank to be just right when locked in rest position - some tweaking/pressing home was needed of the tapered pin.

The main drum orientation is relatively easy - the cut-out of the full-turn gear must point up.

All this being done, so far the machine works all correct. It calculates fine and adds, subtracts, multiplies and divides. One remaining function however that still does not work is the overflow bell - after dealing with the timing, that should be a doddle to fix. (Right?)

In the meantime, started sprucing up the covers. Cleaning and polishing of the decimal markers and brightening the wonderful nameplates. The large nameplate on the back of the machine polished up quite well and the dark green fond came back too :-)