Talk:Quill drive

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DYK	November 13, 2008

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Need a diagram

The photograph of an electric locomotive's truck, while interesting to view, isn't really helpful in understanding the principles of a quill drive. Perhaps somebody could put up a mechanical drawing showing a cross-section or an exploded view? Casey (talk) 12:28, 19 July 2010 (UTC)[reply]

Needs better explanation

I would like a better explanation of what the advantages of a quill drive are and also how they improve performance.

- how does a quill drive help to reduce track forces

- how does a quill drive help a locomotive to run faster?

- more examples of railway locomotive trucks with quill drives

- Please also link to the standard term hollow shaft

Don't know how old this post is, but I agree. The author of the article erroneously states that the drive couples to the locomotives "traction" motors. A Quill drive makes a mechanical connection to the axle, which is why early electric locomotive drive wheels were frame mounted like steam locomotives were. It wasn't until the 1920's I believe, that truck mounted traction motors began to replace the Quill drive. I will look into this further, right now I have a lot on my plate. Djfitzgerald111 (talk) 18:09, 19 November 2013 (UTC)[reply]

Quill drives (in electric locomotives) are mounted to the wheels, not to the axle. Their only relation to the axle is that they are both trying to share the same axis, so one (the quill shaft) has to be hollow and the other inside it. The quill is so much larger than the axle that it allows space for the axle to move vertically within it - this is a limit on the overall suspension travel possible for the axle of the road wheel. Although railway locomotives have so much smaller suspension travel than road vehicles, so this is quite workable. The quill shaft is carried by fixed bearings attached to the motor frame, or even the locomotive frame. One end carries the bull gear, which is the large gear driven by the pinion of the motor or motors (two in the GG1). The wheel attachments use some arrangement of springs, either leaf springs, coil springs in cups, or just elastomers to attach it to the rear face of the road wheel. It's attached to the wheel rather than the axle so as to give a bigger diameter to work with and thus more spring clearance.

Some early AC electric locomotives had large diameter AC motors that were frame mounted. These generally used Buchli drives or jackshafts and coupling rods, rather than quills, but there's little strong reason for this. As motors became smaller (especially with diesel-electrics), it was possible (and desirable for their low CoG) to mount them lower down and this required the concentric quill drive. The GG1s had three concentric shafts: axle, quill and the motor housing. This motor housing also provided the bearing carriers that supported the quill shaft from the outside – as the shaft has to move within the quill, they can't use internal bearings or provide a cannon bearing to carry the axle.

Because the bull wheel has to maintain accurate mesh with the motor pinion, then it's rigidly located to the motor. The attachment to the wheels can be done in one of two ways: either to one wheel or to both. In the GG1, the quill attaches to both wheels with similar springs to give radial and vertical translation. In some other designs, the quill is only attached to one wheel and is allowed to tilt. This has a better capacity to absorb whee movement for less spring movement, although now having to cope with tilt as well as simple translation. These eventually developed into the nose-hung traction motors used today.

There are some good photos on this site: http://www.steamlocomotive.com/GG1/quill.php

Overall, quill shafts are flexible. Some (like these) allow some radial translation, or can convert this radial translation into slight angular tilts. Others, like drill presses, are axially telescopic. A further form is torsionally flexible, usually used to provide a cushioned drive and avoid breaking a mechanism (commonly a supercharger drive).

Andy Dingley (talk) 02:27, 20 November 2013 (UTC)[reply]

It's worth noting that quill drives are a bit of a nightmare construction-wise, as how are the wheels attached? Normally wheels are pressed or shrunk onto journals at the axle ends. This is still possible with the quill drive, but disassembly for maintenance wouldn't be. How can the bull wheel (smaller than a wheel) be replaced? How are the springs arranged so that they can be replaced, working entirely from the outside? Often this required some sort of two-part wheel casting, an awkward complexity. Disconnecting the concentric arrangement (and switching to nose hung motors) made this a lot simpler. Andy Dingley (talk) 11:48, 20 November 2013 (UTC)[reply]

Thanks Djfitzgerald111 (talk) 08:58, 20 November 2013 (UTC)[reply]

Why don't you use this information to comlete the article in question? Djfitzgerald111 (talk) 14:11, 20 November 2013 (UTC)[reply]

Did once (the sense of quill shaft as a torsionally compliant shaft for driving pulsing loads, like superchargers, without breaking), one of the adminkiddies deleted it. There's little point in working on content any more, too many ignorant busybodies, more interested in playing mallcop. Andy Dingley (talk) 20:23, 20 November 2013 (UTC)[reply]

Can understand that. I have another project that I am working on. Much of that was shredded the first time around, however, the latest rendition has met with approval. I was considering working on this topic as time permitted. My assumptions about Quill drives appear to be incorrect, but I still have a strong interest in electric motive power. Djfitzgerald111 (talk) 20:28, 20 November 2013 (UTC)[reply]