Barry Bogs'  1/22.5  scale

Union Pacific  Big Boy  4018

Quartering Drivers - Nov 29th, 2020

Drivers are the most critical pieces of any steam build. No drivers, not project! The drivers were cast with the nickel plated, lathe cut tires on them, and now they needed
to be assembled on to the axles, and quartered to perfection. But how to do this with such large wheels, and gauge them at the same time? The boys were scratching
their head, as the methods they have used in the past on small narrow gauge drivers would not work on the drivers of one of the world's largest steam locomotives.

It was time to talk to the Big Boy master, Mr. Dennis Mashburn! With his expertise and connections, he was able to secure a big hunk of brass, and mill a jig that not
only quartered the wheels, but gauged them at the same time! The axle was pressed on to one of the drivers, and then slipped into the jig and then a removable pin
is then inserted through the crank pin hole, and into a hole on the jig. Now, on the other side of the jig, the other driver is positioned over the end of the other end
of the axle and a second removable pin is inserted through the crank pin hold and into the jig.
The whole assemble is then placed under the arbor press and squeezed together until the flanges both rest on the jig. The removable pins are removed, and the
complete driver is released for the jig. The crank pins that will be used on the engine will be made back at the BLW shops, once the length has been determined,
and then cut and fitted to the drivers. The mill and lathe used in making the driver tires and the jig are pictured here for reference. My thanks to both
Dennis and Kathy Mashburn for the expertise and hospitality that they have given to all the boys in the shop.  
- Barry 

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