Line shaft speed?
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  1. #1
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    Default Line shaft speed?

    Was there a standard RPM or a standard belt surface speed for over head line shafts or were they what ever they happened to be based on the available power source?

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    There doesn't seem to have been a standard, but 200 or 250 rpm seems to have been common.

    Similarly, 200 or 250 was common for countershafts. Most of the Brown & Sharpe machines were in this range with a few 180s on counters.

    Joe in NH

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    Counter shaft speeds can be much lower - 125 RPM in 1901 L&S catalog

    Thanks to Greg Menke for hosting

    http://pounceatron.dreamhosters.com/...gue-H-1901.pdf

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    I think line shaft speed depended on the machines being driven. Woodworking machines usually run faster than metalworking machines. Wood shop shafts probably were 250 to 350 RPM and 200 to 250 is close for a metal shop.

    Bob
    WB8NQW

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    Lineshaft speed is a function of at least several key variables;

    -what the power & speed requirements of the machinery or equipment to be driven off the lineshaft were
    -what the speed and power of the prime mover was (waterwheel, steam engine, gas engine, electric motor, small hydro turbine, diesel engine...)
    -what the length of the lineshaft was going to be. Shaft length along with power to be transmitted and the sizes/weights of pulleys to be mounted on
    the shafting determined shaft diameter. A longer line shaft was subject to deflection from its own weight, weight of the pulleys and belt pull.This
    deflection occured in the static condition. As the shaft reach operating speed, it took on a different value, and also set up bending fatigue in the
    shaft. Bending fatigue is a reality in ANY horizontal line shaft. It is not a question of "if" a shaft will fail due to bending fatigue but when.
    Design a lineshaft heavy enough with a low enough value for bending stress, and the shaft will outlast several generations of people using it.
    As a lineshaft gets longer, things like settling of the building structure upon which the lineshaft hanger bearings are mounted also adds some
    deflection or side-load to the shafting. Floating hanger bearings and adjustable hangers for the bearings are used to deal with this. Old mill buildings,
    framed with timber and having unheated areas on "iffy" foundations were common for this sort of thing happening.
    -lastly, we come to the critical speeds for the pulleys. Pulleys can be large rotating masses. Something like a large mill pulley, made of glued up hardwood
    and made in halves is not something that is properly balanced for higher speeds. We also come to the critical speed at which centrifugal force takes over
    and a pulley can fly apart. For smaller pulleys, made of steel, this was less of an issue. For cast iron pulleys, pulley fabricated by pressed and riveted
    stampings, or wood pulleys, this was more of a concern.

    Generally, lineshafting ran slow. Between some natural shaft deflection along with length and sizes of pulleys, lineshafting turned fairly slowly. If a line of smaller machine tools such as bench lathes needed higher speeds, a second lighter lineshaft might be run parallel to the slower turning "main" lineshaft. This lighter lineshaft would turn faster, and belts for the individual smaller bench lathe countershafts would take off of it.

    Some mills and shops were "vertically integrated" in terms of the lineshafting. The prime mover would be at the lowest level, where it could be founded on a masonry foundation or tied onto bedrock. The prime mover would turn slowly, and a rope drive or wide multiple ply belt would drive the primary shaft, speeding it up as well. Waterwheels used a bull gear and pinion for this first speed increase. The primary belt or rope driven shaft then had some heavy pulleys on it and wide belts ran to lineshafting on the first floor. The heaviest machinery or equipment was located on this floor as it used the most power and turned the slowest. Some belts were taken off the first floor lineshafting and passed vertically up through a shaft or hole in the floor to the next level. These belts drove the lineshafting on the second floor, which turned faster yet, and drove lighter machinery. In some shops, the belting ran up several stories, and each story had successively lighter machinery. In cities, some machine shops were multi-story and fairly narrow buildings. Running belting up a few stories with an engine in the basement was common. Many things determined lineshaft size, and there was no set rule other than basic machine design as far as determining the
    diameter to transmit a given torque at a given speed over a given run with pulleys of known (or approximated) weights and belt pulls acting on the shafting.

    Long lineshafting, when running, is a sight to see and a treat for your ears. The belts slap, the air whirs as the spokes of the pulley fan it, and there may be wire rings on the shafting. These rings are put there to knock off accumulations of dust and oil. The natural deflection of the shafting under load causes these rings to scoot up and back along the shafting, continually as it is running, and they add their own sound.

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    Quote Originally Posted by Joe Michaels View Post
    Lineshaft speed is a function of at least several key variables;

    <...cut....>

    Long lineshafting, when running, is a sight to see and a treat for your ears. The belts slap, the air whirs as the spokes of the pulley fan it, and there may be wire rings on the shafting. These rings are put there to knock off accumulations of dust and oil. The natural deflection of the shafting under load causes these rings to scoot up and back along the shafting, continually as it is running, and they add their own sound.
    Thanks Joe for such a thorough coverage of the principles involved. Using your outline when designing line-shafting, only needs the numbers plugged in to have a top notch job.

    George

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  8. #7
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    My all time favorite Lineshaft video
    Roy Underhill of PBS Woodwright's shop tours a window and sash lineshaft factory. Just awesome machinery from the 1870's all driven by overhead line-shaft.

    https://youtu.be/--HRj25oQgI

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  10. #9
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    Quote Originally Posted by tim9lives View Post
    Wonderful! Paul

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    Watch this one for how to figure out your basic speeds at the spindle, YouTube Dave Richards is a more than knowledgeable guy about line driven equipment.


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