The carriage of both Marchant Pony calculators were partially seized - multiple positions completely unmovable. Additionally, the 18th position of the result-register of the restoration-machine was missing (!), and mangled wingnuts.
At some moment in its past, this machine was radically repaired - repaired from a 'catastrophic event', e.g. being dropped, being hammered. That event is probably also when the main crank was bent, levers broken and the 18th a wheel lost (how??). Not just the numeral-wheel, also its ten-carry lever plus gear was taken out. A small piece of brass was soldered in its viewing aperture in the cover. This was then neatly painted black, making it a 17-digit machine.
As a start, the target-carriage was completely emptied of all parts - the usual stubborn screws and hardened old oil, but also the counter numeral-wheels were jammed solid between the carriage sidewalls. In the end, an empty and clean carriage; a brass casting with a simple steel strip screwed to the bottom as the sliding surface.
No pictures of rebuilding the counter register - this was hard! to do and was assembled and taken apart at least ten times! One surprising feature and difference with the donor-machine were brass plates or shims between all the numeral wheels.
These very thin brass plates were all somewhat mangled, probably from brute-force clearing attempts or perhaps a botched assembly. When this shim is not aligned with the main rod, the clearing-pins would 'notch' the brass as the rod is pushed in - this makes extra thickness and pressure on the stack - causing it to be blocked. It is doubtful that all positions of the counter would have worked well after the old repair.
These shims also made it impossible to exchange some wheels with the donor. To accomodate for the brass shim, the wheels are about 6.75 mm wide, whereas on the donor all wheels are 7 mm wide. Well, they really are just under 6.985 mm. This is an American machine; the pitch of the columns is not 7 mm as they would be on a Continental machine, but on the drawings is given as 0.275". Inches and fractions...
(The making of many parts of the Marchant Pony are shown with good explanations, drawings and photographs of the actual tooling in a great 1919 book on Punches & Dies. The book also shows several stamped parts for the Noiseless Typewriter and some Smith Premier typewriter parts. The book can be found in full on The Archive.)
From both donor and target machine, a glut of numeral-wheels. A total of 35 specimens in various states of wear - cleaned and to be sorted on quality.
Again small differences, the target machine wheels are about 24.5 mm diameter, the donor-wheels are 24.0 mm on average. Probably simply batch-to-batch variation.
Many wheels - a 35 digit register; that'd be a 116-bit register - the actual 18-digit Pony B is already not bad as a ~60-bits computing device :-)
Cleaning, fitting and filing of the the tens-carry levers, then on their rod and screwed in-place. The left-most levers have extra prongs to trigger the overflow-bell (carriage here seen from behind).
After these levers are fitted, the springs and tiny plungers have to be cleaned and fitted to every lever as a rod is pushed in from the left to lock things in-place with an intermediate gear next to every lever.
These are the little spring-loaded pins that keep the tens-carry levers in the out- or in-position. The parts of the target machines are not original - these springs are offcuts of a different size, and the plungers are rounded bits of varying length. Good replacement/repair effort, but not original. The circled three are original Marchant pins with a bevel.
As the rod is pushed in one lever at a time, the springs and pins are selected to give an even, reasonable force needed to flip the lever between positions. Some spring shortened, lengths of pin and springs matched. (Below picture is of a test-fitting, gear-wheel for column 17 needs to be added still.)
Also here the 18th wheel was given a test-fitting - to check if there was something wrong in the carriage-frame, causing the 18th position to be removed. No problems, all works fine. Likely that one numeral wheel or other part was broken, then leaving off the 18th position is the way to solve a lack of parts. The repairer decades ago won't have had a donor machine :)
After the gears-rod is fully inserted and all the intermediate-gears plus all carry-levers are in place, the register can be filled. Starting from the right one position at a time.
To test, first placed on the machine with the first two digits only. The holes vsible on the register main-rod shows that several clearing pins are likely replacements, only few original pins remained. So many pins needing replacement does suggest mis-use; excessive force on the clearing wingnut is needed to shear off these pins - or forcing wheels (perhaps breaking a wheel). The scoring of the numeral wheels also hints at brute-force attempts to move blocked numeral-wheels. This machine really needed to be seriously rebuilt!
The springs for the overshoot-prevention rockers need to be placed with care. When simply pressing everything in place, springs don't enter their pocket and will be mangled and the rocker will be very stiff (blocking?). Several springs were indeed mangled - now replaced with good springs from the donor.
When everything is in place, the front rack-bar can be screwed in-place. The entire carriage is now clean and functional - well, mostly functional.
The clearing-flange of the counter is mounted upside-down; that vane should be at the bottom. With the new wing-nut and the pins being what they are, I simply cannot find a position where all wheels clear and no wheels are fouling when zero. In comparison, the 18-digit result register was easy to get to work.
The gear surfaces that slide over the detents are still rough (hard to polish); excercising the digits hopefully will make things smoother. For now the result is one basically functional carriage of a Marchant Pony B calculator :-)
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