Big old Pratt & Whitney with unidentified features
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  1. #1
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    Default Big old Pratt & Whitney with unidentified features

    My friend just bought this lathe and sent me some pics. It's a big old P&W about 10' long and something like 3 tons, reportedly from the early 1900's. It's in remarkable condition for such an age and comes with all the gears and steadies plus taper turning. I guess it must have been a top-tier machine in it's day.

    pw1.jpg

    pw2.jpg

    We are wondering about some of the unusual controls and features on the carriage and slides.

    pw3.jpg

    pw4.jpg

    The lever under the cross slide handle. What would that be for? I'm guessing either a direction reverser or a quick-retract for the slide? If it's a quick-retract would it be used with a stop rod through that un-used hole in the cross slide screw support casting?

    The small handwheel down by the feed shaft. What is that used for?

    What's the purpose of the rocker arrangement on the compound slide and how is it supposed to be used?

    Can anyone shed any light on these things?
    Thanks
    Pete.

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    Appears to be normal 16" which was made early 1900s to the advent of the Model B in early twenties

    I have never figured out the small hand wheel down low (unless an old version of lead screw reverse), but I'll guess the odd compound is part of a Relieving attachment

    Lathe is covered in this 1911 catalog

    Precision tools : Pratt & Whitney Company : Free Download, Borrow, and Streaming : Internet Archive

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    Thanks for the catalogue link John. They list a quick-retract for threading so I expect that's exactly what the lever under the cross slide screw is. They also list plain- and elevating compound slide rest so I guess this one has an elevating one though it's purpose is not clear. The small handwheel is in front of a rod that seems to have stops on it in the catalogue. A threading knock-off perhaps? I'll see if we can get some good pics of that.

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    Thumbnails from 12 years later in 1923 - it has lost the little hand wheel and shows the Relieving Attachment - and also the rather ugly gear head version
    Attached Thumbnails Attached Thumbnails november-1923_3.jpg   november-1923_4.jpg   november-1923_2.jpg   november-1923_1.jpg  

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    Think these are interesting lathes. And I bet it is heavy too! My old P&W is I think a 13"x54" with no quick change gears and a overhead Lima motor/tranny. Mine came with an original {I think} box of change gears and the complete taper attachment. But looks antiquated compared to the 16" the OP has shared. Another thing I like about his is the chip pan which mine has none. My 1924 Mod B does but is missing the center tub on wheels to catch the fluids and chips. Does look like a nice lathe. Thanks for sharing it.

    Question to OP did you get the taper attachment slide with your lathe? The one I got with my older lathe fits the newer mod B taper slide arrangement which looks like yours. Difference is the tapered stud that fits into compound slide. I would very much like both my lathes to have their own parts but think many of these got separated from the lathes as they got sold and moved around. To OP if you didn't get the slide try real hard to go back and find it and get it. You could make one but the original is a real nice pc of work with adjustable gibs.
    Regards, John.

    Edit/PS in looking closer at the pics the a shadow almost looks like it is in place in the one picture where you can see the taper attachment. Congrats to your friend by the way.

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    Yes, looking at all the pics it's virtually all there and I think the slide is connected to the pin. Looks like even the Jarno spindle adapter is present. I love the double-stacked cross slide that keeps the screw independent of the taper turning operation.

    Interesting that there's no thread dial. I wonder is the small handwheel a leadscrew reverse?

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    The small hand wheel at the bottom of the apron is most likely a quick disengage for both power feed and screw cutting. The trip stops shown in the catalogue pictures move the rod to left or right as appropriate to disengage the feed. Given the appropriate mechanism the hand wheel can do the same job.

    On later machines like my Model B 12 x 30 the equivalent shaft is higher up the saddle and has a lever that turns it through about ± 30° to disengage the feeds. The internal mechanics change the rotation into a longitudinal shift. There are also equivalent trip stops on the rod that move it sideways to automatically disengage feed.

    Clearly if the small handle carries something to rotate the rod when it is turned and the relevant devices to turn that rotation into a longitudinal shift your machine would have a functionally equivalent power feed and screw cutting control system. On my machine the drive engagement and disengagement is done via the single tooth dog clutch. There are various equivalent mechanisms that could do the job but I wonder if this machine does in fact have a single tooth clutch in the drive train. Looks like there may to be room in that feed box. If so it would explain why no threading dial is fitted as, theoretically, there is no need for one when a single tooth clutch is used.

    But if a single tooth clutch is fitted its surprising that there is no mention of it in the brochures.

    Clive

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    This B brochure (predates the 12") gets around to describing lead screw reverse without ever calling it that on page 11 - and even has a dig for Hendey's bevel geared version.

    http://pounceatron.dreamhosters.com/...athes-1936.pdf

    Thanks to Greg Menke for hosting this for me

    On edit - be nice for you and your friend to explore the function of the small hand wheel - like maybe it DOES actuate lead screw reverse with spindle turning at a low speed

    Or maybe it just clamps down on the bottom most rod for whatever reason
    Attached Thumbnails Attached Thumbnails earlyapronpw4.jpg  

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    If it simply clamped the apron to the rod the effect would be functionally identical to the trip stops clamped onto the rod. Just under manual control. Given that such trips, especially simple dog clutch ones, are always a bit imprecise there seems no advantage in providing the hand wheel. The lathe seems to have the usual star wheel operated clutches in the feed drives which would be equally effective at dropping the drive and more repeatable in skilled hands.

    Still think it may be a step in the evolution of the single tooth dog clutch system used on later machines.

    Clive

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    Here's a couple of shots cropped from other photos. That's all I can get until later in the week.

    pwhandwheel1.jpg

    pwhandwheel2.jpg

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    Useful pictures. Especially no 2.

    Look to be gear teeth on the bottom of the rod and a spindle below it. Hand wheel spindle above. So assume a gear on the hand wheel spindle big enough to reach down past the rod and engage in a wide gear that also meshes with the gear teeth on the rod. Turning the hand wheel will move the rod back and forth. Three positions arranged as centre off, rod to right selects left feed, rod to left selects right feed gives same feed direction and trip functions as the system on the later machines like mine.

    Whether on not it has a single tooth clutch in the drive the system is clearly a step on the way to that used on mine. Being hung down like that its obviously a minimum modification redesign of an older, two shaft, machine without the control rod. Despite the re-positioned, lever operated control rod on the later machines the basic apron control layout remained pretty much the same although mine has an integrated threading dial with more sophisticated than usual markings.

    The Pratt & Whitney design team clearly had a minimum change attitude. If it works keep using it. Not a bad approach in general but I'd have been happier they'd dumped the star wheel control clutches for nice levers on the Model B instead of waiting for the C. About the only feature that seriously annoys me. Quick retract arrangement is aesthetically better but I'd be unsurprised if lever operated version on this machine wouldn't be easier to use.

    Clive

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    Very educational Peter - thank you. So - likely lead screw reverse via twisting a hand wheel instead of moving a lever up and down thru three positions as later. I wonder - even with the bottom situated rack teeth - if there was ever any problem with hung up chips/trash tending to make the system self acting

    His is my old write up on Hendey's, which used the lever idea. Starts at Post #17. The capabilities - if not considered before - are rather mind boggling

    Hendey lathe "emergency"!

    ph

    Quote Originally Posted by Peter. View Post
    Here's a couple of shots cropped from other photos. That's all I can get until later in the week.



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    I agree with the other that the lower hand wheel is the means to shift lead screw reverse. It was probably an optional attachment since one of the photos John posted shows a similar lathe without the hand wheel but has a bracket for the adjustable stops to butt against. The newer version has a rod in about the same location that now operated the clutch. The right/left movement now a up/down movement is created by the spiral located in the casting mounted on the tail stock end to support the lead screw and other rods.

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    Quote Originally Posted by Froneck View Post
    I agree with the other that the lower hand wheel is the means to shift lead screw reverse. It was probably an optional attachment since one of the photos John posted shows a similar lathe without the hand wheel but has a bracket for the adjustable stops to butt against. The newer version has a rod in about the same location that now operated the clutch. The right/left movement now a up/down movement is created by the spiral located in the casting mounted on the tail stock end to support the lead screw and other rods.
    Morning everyone.
    I have just signed up to the forum.
    I am the owner of the pratt and whitney lathe. Many thanks to pete who posted the pictures on my behalf. And thanks for the information you guys have given. Very appreciated. I will get some more pictures.

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    Quote Originally Posted by Spencer427 View Post
    Morning everyone.
    I have just signed up to the forum.
    I am the owner of the pratt and whitney lathe. Many thanks to pete who posted the pictures on my behalf. And thanks for the information you guys have given. Very appreciated. I will get some more pictures.
    And thank you for providing the means for educating us


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