email: tony@lathes.co.uk
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HARRISON 140 Lathe
A manual is available for this Harrison lathe
Flat-belt Drive L2   An Original L5
Harrison Home Page   L5 Early Model   Later L5 9" & L5A 11-inch"   140   
L5 Accessories   
10-inch   Late 10" & 12" L6   Early 12" L6     Late L6 Mk. 3   
13" & 15" Late Models    13"   14"   16"   17"    Hydraulic Copy Lathes
Harrison Union Lathes   Models 155 and 165   Model 190
14", 16" & 17" Accessories
Newer Models
:
AA-10 VS  VS330 & AA   M250   M300   M350 & 390   M400   M450   M500


Named after its swing of 140 mm (11 inches) the Harrison 140 was produced late in the life of the L5A/11-inch series. The lathe was mechanically identical to the earlier machines except for a squared-off headstock which may have contained slightly altered gear ratios. The front of the headstock was flat and carried a large rectangular plate on which were engraved the spindle speeds and either Harrision 140 or Harrison 11". The latter name was also used on the "round" headstock version - but on a narrow nameplate immediately below the high/low speed selection lever. The 140 is likely, from its name and the numbers encountered so equipped, to have been sold  largely as an all-metric machine, with an all-metric screwcutting gearbox - identifiable by a row of three aluminium "thumb" lever is a row across the top edge, the Imperial box having just two. Each box could, of course, with the right changewheels in place, be converted to the other type of pitch (though it's important to note that the Imperial (inch) box models were equipped with a 4 t.p.i leadscrew. Certain differences exist between the various screwcutting gearboxes in the L5, 11-inch and 140 Model range and if you have a 140 it is essential to have the right manual that lists the changewheel (and gearbox) combinations correctly. The gears inside the metric box were identical to those in the "inch" version and the two (left hand) thumb arranged the same 2:1 ratio stages. The third (right hand) thumb lever did not (as on many other makers' boxes) engage the leadscrew or fine feed drive, but instead switched between a pair of 21t/21t and 21t/20t gears to give an increase in pitch of exactly 1.05:1. Harrison clearly, in saving money by using the imperial internals, had made this modification in order to obtain a reasonable number of metric pitches. In addition. there might have been  a 2:1 speed increase in this third stage as the input changewheels reduce the input speed by that ratio (and the table of imperial threads printed in the manual is actually the reverse - a mirror image - of that obtained from the tumbler lever (that's the one fitting into a line of 9 holes). Unusually compact (engineering speak for too small) the gearbox suffered from the lack of a lubrication sump, oil having to be squirted in by the operator - when he remembered. While the rest of the lathe was heavily built if a fault is to be found in a well-used example it will almost certainly be within the gearbox - and so a careful inspection of this component, and a run through all the lever positions under power, is strongly advised.
The only external differences between the 140 and the 11-inch was the shape of the squared-off, flat-fronted headstock casting; the headstock internals appear, however, to have been arranged in an identical fashion to those of the L5A and 11-inch models - although it is possible that some minor alterations were made to the gear ratios. Although the majority of 140s seem to have been built with a top speed of less than 1250 rpm they were fitted as standard with the special (and improved) two ball-race supported clutch originally provided on the earlier 2000 rpm "high-speed" headstocks. It appears that all 140 models were equipped with the American long-nose taper spindle nose - though it is entirely possible that a customer lost their mind and ordered instead the threaded spindle nose offered as an option on the "11-inch". To discover more about the general design and arrangement of the 140, refer to the L5A and "11-inch" pages..




The inner and outer changewheel covers and door were identical to those on the L5A and both the clutch and high/low-speed levers fitted with a spring-action safety "gate" that prevented them being accidentally knocked into the engaged position.

The distinctive front to the headstock of the Harrison 140

Later 140 lathes were offered as "all-metric" machines with a metric-pitch leadscrew and a proper metric screwcutting gearbox; these improved lathes, in both metric and English-screwcutting form, can be recognised (even if the plates are missing) by a third thumb lever to the right of the usual two on the front face of the box; this lever was used to select the engagement of either the leadscrew or power shaft, the previous rather old-fashioned external dog clutch having been removed to allow both shafts to be protected by spring-loaded overrun clutches that were built into the bosses where the shafts entered the gearbox; this protection of screwcutting and feeds was considered a wise precaution on machines intended for training workshops full of impatient, teenage apprentices.
The rectangular plate on the front of the gearbox was held on by two thumb screws and reversible; one side was engraved with the settings for coarse pitches, the other side for fine; to convert the gearbox from one range to the other a set of gears, supplied as standard with the machine when new, were mounted on the changewheel bracket..




email: tony@lathes.co.uk
Home   Machine Tool Archive   Machine-tools Sale & Wanted
Machine Tool Manuals   Catalogues   Belts   Books  Accessories

HARRISON 140 Lathe
A manual is available for this Harrison lathe
Flat-belt Drive L2   An Original L5
Harrison Home Page   L5 Early Model   Later L5 9" & L5A 11-inch"   140   
L5 Accessories   
10-inch   Late 10" & 12" L6   Early 12" L6     Late L6 Mk. 3   
13" & 15" Late Models    13"   14"   16"   17"    Hydraulic Copy Lathes
Harrison Union Lathes   Models 155 and 165   Model 190
14", 16" & 17" Accessories
Newer Models
:
AA-10 VS  VS330 & AA   M250   M300   M350 & 390   M400   M450   M500