Although not as well known as some manufacturers, by the late 1950s Mondial S.A. Constructions Mechaniques of Vilvorde-Bruxelles in Belgium had sold over 30,000 lathes. The examples shown on this and the next page were manufactured during the 1940s and early 1950s and marketed using the "Simplex" brand name. They were well-made, V-bed machines, constructed to Salmon and Schlesinger limits, and offered in two sizes with swings of 10.25 inches and 14 inches; the smaller model was built in two bed lengths with the 'Type JS' offering 19 5/8" between centres and the 'Type KS' 31 1/2".  The lathe was very heavily built for a 10-inch machine, with a construction at least as massive as a Harrison L5A although, unlike that versatile machine, no gap bed was offered. The cast-iron stand held a swinging countershaft assembly with an over-centre locking device; a two-speed motor - with 0.75 hp at 1500 rpm and 1.3 hp at 3000 rpm - drove the countershaft via a V belt - with a flat-belt final drive to a 4-step headstock pulley; a total of 16 speeds was available: in backgear these were: 50, 72, 98, 108, 145, 160, 216 and 320 rpm and in open drive: 245, 360, 490, 540, 725, 800, 1080 and 1600 rpm. The 11/32" bore, No. 4 Morse taper headstock spindle (with a nose thread of 45 mm diameter and 3 mm pitch) ran in Timken taper roller bearings.
The double-walled apron was fitted with a pumped oil supply system and used Mondial's unique system of a vertical power shaft, with helical gears, to provide an extra-smooth drive. The feeds were engaged and selected by a single quadrant-type lever on the face of the apron - a convenient system, but one which, due to loading pressures, mitigated against an instant withdrawal of the feed; as a safety feature an interlock was provided to guard against the alternative feed being accidentally selected as the lever was moved out of its engaged position and swung into neutral.
The Norton-type sliding-gear screwcutting and feeds gearbox provided 43 English threads from 3 to 80 tpi with one setting of changewheels - and by combining three sets of gears an additional 20 metric threads could be generated. The longitudinal (sliding) feeds ranged from a slow rate of 0.0016"  to 0.048" per revolution of the spindle and the transverse (surfacing) feeds from 0.0008" to 0.024".
The set-over tailstock, with an inadequately large No. 2 Morse taper, was clamped to the bed by a central nut - the loose spanner for which would either have been lost or hidden by an apprentice on the day after the machine's installation.
The 14-inch lathe was laid out along very similar lines, with an underdrive, flat-belt countershaft,  but could be had with  20, 30, 40 or 60 inches between centres - and with the swing increased to 16-inches by special order.
Later Mondial Simplex lathes of the 1950s were recognisable by their squared-off headstock, tailstock with an angled spindle drive and the fitting of a variable drive system inside the left-hand cabinet plinth. If you have one of these machines, or any literature about them, the writer would be pleased to hear from you.