The Queensland Clyde-EMD locomotives, GL26C (2100 and 2200 classes) GL22C (1550 and 2400 classes) and GT22C (2301 class) all use the EMD D29 motors. It was similar locomotives in Tasmania that were fitted with EE motors which were thought to be a bit stronger. The D29 has been replaced in new designs for “Universal” (narrow gauges down to 1 metre) applications by the D43.
The Mitsubishi motors (and generators) were used from new in six DL500G type, 44235 to 44240 and in fifty similar CE615 units 8001 to 8050. I think these motors were designed to suit the MLW Dofasco design trucks used on these units.
Peter, do you have any information, or site URLs, that describe the exact differences between the Dofasco and Alco Hi-Ad trucks? I think I’ve been confusing the two somehow. Do they both have the full-outside-sprung bolster, longitudinal strut, etc.?
No, only the Alco Hi-Ad looks like your above description. The MLW Dofasco looks like a heavy, short wheelbase version of an EMD “Flexicoil”, about as plain as you could imagine. I wrote an article describing these in an early issue of the Australian magazine “Motive Power” but that’s not going to help you much.
I tried to check a local website but it seems to be down for an update right now.
If you check the “BHP” and “Private mining railway” pages, the lists and illustrations of C636 and M636 and GE CM40-8M units should illustrate both types of trucks (although there may be some confusion between types, particularly C636 and M636. This is due to the operations being as far away as you can get from population centres. The entries for “Pacific National” ex “FreightCorp” units, classes 442 and 80 should show the MLW Dofasco in a lighter weight version, still with the short wheelbase.
This will be more accurate. I’m in regular touch with both websites. Right now, in that area, only the Pilbara Rail, ex Robe River CM40-8M units are still in traffic with MLW Dofasco trucks, and many of those units (as rebuilds) were built on C630 or C636 frames with Hi Ad trucks, as well as some using M636 frames with MLW Dofasco trucks. The road numbers were retained, but they are intermixed numerically!
is one of the Dofasco trucks. Exactly, I might add, as you described.
Doesn’t look like it has very sophisticated secondary suspension at ALL! What’s up with the bracket I see between the top of the truck frame and the locomotive frame directly over the center axle?
Bingo - Robe 9410 to 9416 are or were M636 with MLW Dofasco trucks. One of the rubber -metal sandwich secondary suspension pads is visible midway between the rear two axles. Not big but it works! There are a number of horizontal dampers, one of which is visible above the frame between the front two axles. The support pads nearer the end of the loco are inboard of this damper on a frame cross brace, which also provides the location for the pivot which supports no weight but has longitudinal rubber springs fore and aft. I think the bracket visible above the truck midpoint is the body bracket for the inner horizontal damper. One reason BHP didn’t like these trucks was that the ride deteriorated with wear on the dampers.
The secondary suspension on the GE Hi Ad is the same as the MLW design, obtained when GE bought MLW. It must work reasonably well even if it doesn’t look “Sophisticated”.
So that is the same Dofasco that is on the Milwakee Road SDL39s yes? And then a regular Alco Hi-ad is the one that is on all (majority) of American C630s and 636s.
Has anyone come across a good loco truck identifier web site? Aren’t there 3 or more versions of the HTCRs.
The trucks on the SDL39 (and on the Saudi Arabian SDL50) are the EMD GLC model (I think) an export design dating from about 1960. It is more like a short wheel base version of the standard three axle “Flexicoil” used on pre Dash 2 units. The axle spacing is uneven, with the outer two axles closer together. It does not have the motor arrangement of the MLW Dofasco (all motors on one side of the axle) and has a conventional bolster. The last new design I’ve seen with this truck was the Irish JT42C, numbered in the series from 201.
As far as C630’s are concerned, only the four C&O units had the Hi Ad, all the others in the US and Mexico being fitted with the older Trimount design. Canadian C630s had the MLW Dofasco.
The HTC-R trucks on the export JT42CWR (British Class 66) are quite different in appearance to those on domestic units. Australian units use a different fabricated design that looks more like a GE truck. There may be other differences in appearance I’m not familiar with.
I don’t know of a truck website, but the old Diesel Spotters Guide and the new Field Guide have clear truck photos.
The MLW Dofasco was developed for CN who still had quite a bit of poor quality track left over from their formation in 1920 from every bankrupt railroad in Canada. The intention was to produce a three axle truck with lateral curve forces no worse than a two axle truck, which would allow more powerful locomotives on lighter track.
According to test results I’ve seen this was achieved, more or less, by the MLW design. The shorter wheelbase helped, as did the off centre pivot and the relatively soft (laterally) secondary rubber pads. The reduction in lateral force on the leading axle of the trailing truck in a curve was particularly marked, when compared to an SD40. The reduction on the leading axle was not as great, but the reduction in total lateral force greatly reduced the chance of turning a rail over in a curve. It probably cost more than the Trimount, however. I don’t think any US railroad ever considered them, even though they were in use at least a year ahead of the Alco Hi Ad. Conrail leased a number of CN units fitted with them for use in Pennsylvania and West Virginia, but didn’t ever test them to my knowledge. Of course Alco might not have offered them. Considerable frame redesign was needed to fit the MLW truck (although this had been done in Canada anyway). Even if the truck had been offered, it might not have affected Alco’s rapid decline at that time.