Re: T-12 Frame-Bearing-Driver Fit Check

John Stutz

  • On December 5, 2021 7:21 AM Bill Lugg via <luggw1@...> wrote:
Are the real rods only 2" thick?  ...
I don't know about the T-12, but Modern Locomotives 1900  has details of a few  main and side rods.  There is nothing equivalent for any of the narrow gauge locomotives illustrated, but the tables do give the main and connecting rod pin/bearing sizes, and these are more or less indicative of the rod dimensions.  As are the weights on drivers, which determines the maximum tractive effort, and load on the rods, for conventional steam locomotives.

Note that it was common for 4-4-0's and 4-4-2's to have their main rods inside of their connecting rods.  This only works when the main rod conects to the leading driver, so is very rare on other wheel arrangements.  The significance is that the inner rod must have a bearing diameter equal, and preferably larger, than the outer rod bearing.  When two side rod bearing sizes are given, the larger is at the main rod pin, and the smaller at the outer driver pins.

For detailed information on late 19'th century locomotive construction, get a reprint of "Modern Locomotive Construction 1892", by Arnold Meyer who was a senior designer at the Brook's.

Locomotive #2, a 16"x24" cylinder, 74,000 lb on 66" drivers, CM&StP 4-4-0 of 1895, with 5.0x4.25" main rod bearings and 4.0x3.5" side rod bearings:
Main - I-section 2.25" x 4.75" at the big end, tapering to 3.375" deep at the crosshead, big end 3.0"x 7.75" in the head, 4" wide  x 7.5" x 10.25 over the brass. 
Side - I-section 2.5" x 4.25" throughout, heads 3.375" x 7" diameter with pressed in brass 4.016" ID & 5.25" OD.

#101, a 19x24", 100,600lb on 50" drivers B&O 0-6-0 switcher of 1895: 5.0x6.0" main and 5.75x4.25" & 4.0x3.5" side rod bearings. 
Side rods rectangular 1.75x4.0", 4.5x10.5" diameter center head, 3.25x8.5" diameter outer heads, articulation 6.75" diameter with 2" tongue and 0.875 jaws slightly tapered, all with pressed in circular brasses.

Most entries lack any detail regarding more than the rod bearing sizes, but the above gives some indication of how the rod dimensions relate to the bearing dimensions.  Bearing sizes are given as inside diameter by length. the following are for some of the narrow gauge locomotives, which were running a bit larger than those built for Colorado in the 1880's.

#23, a 14x18" cylinder, 52,000lb on 46" drivers, meter gauge EF Central do 
Brazil 4-4-0 of 1894: 2.875x2.875" main and 2.75x2.75" side rod bearings.  Main rods inboard of side rods.

#53, a 17x20" cylinder, 75,700lb on 42" drivers, 3' gauge Guatemala Central OF 4-6-0 of 1894: 4.5x5.0" main and 3.5x3.0" side rod end bearings.  Very like the White Pass & Yukon 59, 60, 66 & 67.

#76, a 17x2" cylinder, 79,000lb on 37" drivers, 3' gauge Mexican Southern OF 2-8-0 of 1892: 4.5x4.5" main, 3.0x3.0" & 4.5x3.5" side rod bearings.  Roughly a D&RG ex. Crystal River C-21.

#81, a 14x20"cylinder, 61,000lb on 36" drivers, 30" gauge Hormiguerro Central (Mexico?)OF 2-8-0 of 1895: 4.0x4.0" main and 3.0x3.0" & 4.25x3.75" side rod bearings.

#94, a 17x22" cylinder, 79,000lb on 44" drivers, 3' gauge Quincy & Torch Lake 2-6-0 of 1895: 5.25x4.25" main, 3.5x3.5" side rod bearings.

#97, a 13x18" cylinder, 40,000lb on 30" drivers, 30" gauge Pacamayo & Huanchaca (Bolivia) OF 2-6-0 : 3.5x3.5" main, 3.0x3.0" & 3.75x4.75" side rod bearings.

#123, a 16x20" cylinder, 80,000lb on 36" drivers, meter gauge EF Central do Brazil 4-8-0 of 1894: 4.5x5.0" main, 4.75x4.25" & 3.5x3.5" side rod bearings.  Very Brooks and slightly larger than the Fremont, Elkhorn & Missouri Valley 4-8-0-s.

#141, a 16.5x20" cylinder, 70,000lb on 37.5"drivers, 42" gauge Costa Rica Ry OF cab-forward 0-6-4t of 1892: 4.25x4.25" main, 3.0x2.75 side rod bearings. A helper to supplement the standard IF 2-6-0 road engines.

#142, a 14x18" cylinder, 56,500lb on 36.5" drivers, 30" gauge Antofagasta Ry (Chile) 0-6-2t of 1892: 3.5x3.5" main, 3.75x4.75" & 3.0x3.0" side rod bearings.

#157, a 10&17x22" cylinder, 51,100lb on 60" drivers, 42" gauge Sanyo Ry (Japan) 2-4-2 of 1894: 4.25x4.25" main, 4.5x3.5" & 3.5x3.5" side rod bearings.

#188, a 10&17x20" cylinder, 64,500lb on 41: drivers, 3' gauge United Verde & Pacific 2-6-0 of ??: 4.25x4.25" main, 4.5x3.5" & 3.5x 2.75 side rod bearings.

#189, a 7.5&13x18" cylinder, 34,780lb on 41" drivers, meter gauge E.F. Melhoraintos NO Brazil 2-6-0 of 1894: 3.25x3.5" main, 3.75x3.0 & 2.5x2.5" side.

#190, a 10&17x20" cylinder, 57,240lb on 49" drivers, 42" gauge Wellington & Manawatu (N.Z.) 2-6-2 of ??: 4.0x4.0 main, 3.0x3.0" side rod bearings.

#201, a 7&12x16" cylinder, 34,520lb on 33" drivers, 2' gauge RF Campinaro (Brazil) 2-6-2t of ??:  3.0x3.5 main, 3.25x2.5" & 2.5x2.5" side rod bearings.

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