Harrison 140 speed selector

[mark roberts 7Participant @markroberts7]

I recently aquired a 140 and have been having some problems engaging different speeds. It has two levers on the top, and a high/low lever on the front. The right hand lever becomes solid and wont move and occasionally will become unstuck.

I have found if rotate the chuck by hand I can position the left lever in a neautral position which makes the right lever free to move. I cant imagine it should be this hard in selecting speeds, I feel like I'm trying to crack a safe feeling for gears to disengage whilst fiddling around with levers

[mark roberts 7Participant @markroberts7]

[SillyOldDufferModerator @sillyoldduffer]

I don't know about the Harrison, but lathe gearboxes are often basic and don't support changing at speed. Although mine usually changes OK at slow speed, I've got into the habit of stopping and rocking the chuck to and fro until the teeth align and there's no chance of a crunch. The advantage is reliable low cost, the disadvantage is time-wasting gear changing. This may not be a problem at all.

However, a posh lathe might save operator time by fitting a sophisticated gearbox that he can change on the fly. The disadvantage is cost and the possibility the box will eventually get out of order and need expensive repair. We need a 140 owner to explain what sort of box the machine has. If primitive, the behaviour could be normal – just slow down or stop to change gear. If the gearbox is high-end, and it must be fixed, this might be painful.

One of the things that put me off buying a really good second-hand lathe was the high cost of spares and the risk they might be Unobtainium. Whilst high-end lathes are available at delightfully low prices, spare parts are often still full-price, that is eye-wateringly expensive. So fingers crossed!

Dave

[noel shelleyParticipant @noelshelley55608]

As Dave has said lathe gearboxes are usually basic in design ! Rocking the chuck to select a gear I would consider normal, one thing that make this harder is if the wrong oil is in the box and the gears, splines or selectors have become gummed up over time. Another thought is that detent balls or springs have got sticky ? Under NO circumstances try to change gears whilst the box is still spinning, the noise is horrible and such action will soon wreck the box ! Good Luck. Noel.

[Dave HalfordParticipant @davehalford22513]

The below is on Lathes.etc

Selecting Spindle Speeds
Because the control levers were "interlocked", to prevent the engagement of two gears at once (and work in a rather unusual way), it is not always clear to a beginner how the spindle speed should be changed; here is the method of operation:
each of the two selector on top of the headstock can be placed in one of three positions
to select a new speed, either of the two levers must first be placed in its central, or "neutral", position
the other lever can then be turned to either its full-left, or full-right position
by juggling these positions (one lever in neutral, one engaged) new speeds are selected.
However, don't expect the speed-indicator diagram to help you determine which setting you have selected – it's a masterpiece of convoluted lines and what appear to be randomly placed numbers and certainly not something that can be taken in at a glance. Before either selector lever can be moved it is often necessary, as on any gearbox with straight-cut teeth, to ease the spindle round a little to permit the gears to engage. A third, much larger lever, pointing upwards and located on the headstock front cover was used to select the high and low-speed ranges. On early models this lever had no protection against accidental movement but later a spring-loaded safety lock was incorporated that meant the lever had to be pulled out before its position could be altered.

[mark roberts 7Participant @markroberts7]

Many thanks for the comments, I think I get it now Dave. I thought you had one lever in one gear and then altered the other to obtain a new speed but by the sounds of it you choose a side to use whilst the other is in neutral.

[DC31kParticipant @dc31k]

In case you have not found it just yet, the best manual I have found for the machine is this one:

http://vintagemachinery.org/pubs/detail.aspx?id=27367

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