Move the reverse yoke back and forth the valve should not move. To check the measurement of the eccentric rod, set the crosshead on front dead-center.Move the eccentric crank until both show the same measurements. Repeat the operation with the piston on the back dead-center. Measure from the center of the pin in the gear connecting rod to the center of the pin in the eccentric crank. Use a pair of accurate dividers: set the position on front dead-center (by turning the drive wheels).Set the gear connecting rod in mid position, so that the reverse yoke swings back and forth without moving the bell-crank.60 drill hole in the center for dividers. make two "dummy" pins, one for the gear connecting rod lower pin hole and one for the eccentric crank pin hole, these pins to have small No.(This measurement should be obtained by turning the drive wheels by hand. Get front and back dead-centers on crosshead and mark these positions on crosshead and mark these positions on crosshead guide with a fine scratch line.Rules for Timing Locomotives with Baker Gear The prototype NKP engines used Pilliod needle bearings while some other roads did indeed use bronze bushings.īaker valve gear bushing drawing from Baldwin. The prototype used "fiber" thrust washers. These pin and bushing sets were probably the first use I made of commercial CNC work. The design seems to have worked out well as there are many gears out there with many miles on them and showing little wear when using light machine oil on the gear pins. Non-metallic thrust washers were used between interfacing bronze parts. The retainer pins sometimes were made to look like Alemite grease fittings as used on the prototype. Since you shouldn't press bronze bushings into bronze castings, I made precision slip fits between the castings and bronze bushings and then used bushing retainer pins to keep the bushings from rotating in the castings. Basically I have precision machined drill rod pins running in 660 bearing bronze bushings. Here's some photos of the pin and bushing sets that I made for the Baker Valve Gear and sold along with the gear if a builder wanted them. Jim Kreider posted on Facebook, August 2018: Friend, from " The Miniature Locomotive", May-June 1953. Baker valve gear drawing for 1-inch scale SP Atlantic by Lester D.
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