Side-rod diesels

snipped-for-privacy@aol.com spake thus:

I always assumed that it was because only one set of wheels was powered; can't think of any other purpose for them.

"Non-electronic anti-slip device".... Also, in the earliest versions, the electric motor drove a blind shaft that was connected to the wheels by side rods.

Same as on a steam engine or some electrics (PRR VGN N&W), to transfer power from the driven axle to the others. Later traction motors were smaller and did away for the need for this.

Ding... The traction motor technology was such that they were huge back then. Like the GE 44 Tonner started out as a side rod loco. Then as they developed better traction motors, they were able to put 2 motors per truck.

Or so i was lead to believe...

snipped-for-privacy@aol.com schrieb:

That's used on diesel locomotives with hydraulic transmission to get the power to the wheels. More modern locomotives usually have cardan shafts instead. Dieselelectric locomotives typically have one traction motor per axle.

Siderods are usually found on older shunters (up to the 1960s), not on locomotives for higher speeds, as they will run more smoothly without weights moving up and down.

Largely true as stated, but siderods are still around.

Early traction motors were too large to fit between locomotive frames (or axles), so had to mounted on top the frames. These were inherently high torque low "RPM" motors, and no gear reduction was neccessary or desired, so a direct siderod drive made lot of sense. As motors got smaller, and increased in speed, gear drives became more competitive, and eventually won out.

For applications requiring relativly high tractive effort compared to horespower (switchers and industrial locos for instance) often one motor is sufficient, but you want to power several axles. You could use gears, or chains, or siderods. While ALL these systems were and are used, it turns out that siderods are a very simple and effective way to do this at low speeds. Probably the best exampel of this type are the GE-45 ton center cab locos. They look almost like the popular 44 ton models, but (usually) have siderods (a few have chain drive, like the "Steel Mill Specials"). The 44 ton locos have four motors (one per axle), while the

45 ton have only two motors (one per truck). With all axles being powered, and comparable weights, they both have similar pulling power. The 44 ton can potentially operate at higher speeds (more motors, better balance), but is more complicated. If only low speeds are needed, the simpler 45 ton loco is more suitable.

Also, siderods can have some advantages over even gears. A properly phased and balanced set of siderods (usually three at 60 degree phasing) can transfer rotary motion from one shaft to another *VERY* smoothly, and with almost no backlash. Chains and gears always introduce harmonic distortions. While this is of little importance for the case at hand (locomotives), don't write off siderods from a performance standpoint. Like all such things, they have their advantages and disadvantages.

Dan Mitchell ============

But ... one does not always WANT two motors per truck, if ONE will do! The additional motors are just added cost, complication, and maintenance. The 44 ton loco did not 'replace' the 45 ton loco, but supplemented it. Each has it's place.

p.s. ... the one ton difference in weight is not a reality, but a subterfuge to avoid certain regulatory issues. Either loco could be orderd ballasted to any reasonable weight the buyer wanted.

Dan Mitchell ============

Yes, it is higher speeds that have made the siderod drives less deisrable in today's operation. Siderods have balance issues at higher speeds that are difficult to overcome. Changing times, changing requirements. However, many can still be found in service that is inherently low speed (mostly industrial operations).

Dan Mitchell ============

. . . oops!

(all under

The Type 08 diesel shunter was extremely common in Britain in the 50s and 60s:

Not beautiful, but they worked.

Daniel A. Mitchell spake thus:

So what I want to know is, can I add siderods to my U-boat? Would that be prototypical? Could I use Bowser parts?

Well . . . . you could, assuming you can find siderods with the correct hole spacing.

Don't forget to rotate one wheel on each axle 90 degrees so you don't bind them. Oh, also don't forget to take into account the weight of the counterweights.

I think that is all. I am sure that others will add more if I forgot anything.

You can add larger cylinders in front and call it a compound.

They still do all around the former British Rail network. There were a few variants . One was a higher speed version so they did not spend as much time occupying main trackage.Another was two units permanently coupled together only one having a driving cab. used only in one location at a hump yard. The Netherlands railways also used them in large numbers and may still have some in use. An HO Model is avaliable , by Roko I think. A handful were also used in Australia by Victoria railways,yet another variant as these were 5ft 3" gauge.

G.Harman

Another mob that used the Eng. Elec. 350 h.p. 0-6-0 side rod d.e. shunters was the KTM (Malayan Railways). They got 20 of them in 1948, metre gauge. They had a more rounded body than the British locos. Regards, Bill.