Largest of the Riva vertical milling machines made during the 1960s and 1970s was the V20 - also built as a 3-dimensional hydraulic copy version, the V.20.c. Both versions had a 1500 mm x 350 mm table with three 18 mm T-slots spaced on 80 mm centres. The longitudinal movement was 1200 mm, across 400 mm and vertically 600 mm (using a telescopic protection sleeve) with 18 rates of power feed from a separate 2.5 h.p. motor and gearbox unit. Rates for both horizontal travels ran from 12 to 620 mm/min and vertically from 3 to 155 mm/min. rapids were fitted to each axis: horizontally in both directions at 2000 mm/min and vertically at 500 mm/min. All the table feeds and rapids were controlled through electromagnetic clutches (built as-one with the positively-lubricated feeds-gearbox) and switched by pendant-mounted push-buttons. To aid coarse settings, both horizontal movements were fitted with finely engraved rulers (in addition to the usual micrometer dials) and the longitudinal screw equipped with a backlash eliminator to take out snatch when climb milling. Because the table was comparatively long, in order that the operator could stand and observe the cut, the table's longitudinal feed handle was set not at the end, but to the right of the knee where it protruded, at an angle, from the table-support casting.
Powered by a 10 h.p. motor held in the bottom of the main column, the drive passed upwards by three V-belts to a 5-shaft speed-change gearbox holding hardened and ground chrome-nickel steel gears lubricated by a pressure pump. Control of the drive was by a single-disc electro-magnetic clutch and a single-disc brake - both claimed to be maintenance and adjustment free. The ISO 50 taper spindle was made from case-hardened and ground chrome-nickel steel and ran in two high-precision taper-roller races - with a ball race at the back to help support the externally-mounted, dynamically-balanced flywheel.
Able to be pivoted 90° each way from upright, the head was tilted by fitting a crank handle (or handwheel) to a square shaft at the top of the column. This is connected, via a helical gear, to worm-and-wheel gearing.  Only a fine-feed handwheel was fitted to control the spindle movement, there being no quick-action, lever-feed mechanism.
For the V20 a range of accessories similar to that offered for the smaller V6 was listed - one of the most handy, the Vertical Head Extended Projection, being a device to extend the spindle line outwards to give a throat increase from 450 mm to 650 mm. The unit consisted of a small right-angle gearbox that clamped around the end of the spindle flange with sets of bevel gears to turn the drive through two right-angles. To add to its usefulness, the assembly could be rotated in each plane through a full 360°. Also clamped to the same location was the Coxial High-speed Head, a device driven by it's own 2-speed, 0.4/0.6 h.p. motor that gave speeds from 2500 to 5000 r.p.m. motor. Obviously intended only for delicate work using very small cutters, this device allowed the miller to be used for such jobs as die sinking and pattern cutting. For further work on dies, the makers offered the 100 mm stroke Inclinable Slotting Attachment - this  used a right-angle gearbox driven from the vertical spindle set on its lowest speed. Horizontal milling was catered for by the Horizontal Milling Attachment, a bevel-gear driven accessory  carried on the spindle end; a most unusual accessory was offered for this unit - a second parallel spindle that bolted to the underside and allowed milling cutter of up to 50 mm diameter to be mounted, the device being intended to mill racks and slots.  Also able to be mounted, using a special bracket, was the T.V.U. High-speed Head, the same unit as employed on the smallest of the company's horizontal and universal millers, the Types U.2 and O.2. This had a lever-action quill with the spindle driven by its own 2-speed, 0.6/0.4 h.p. motor that gave, via V-belts, speeds of 500, 750, 1000, 1500, 2000 and 4000 r.p.m.
For production work needing frequent tool changes a powered draw bar could be fitted: this had a positive in and out action and allowed cutter to be changed with comparative ease. Another device to improve piece-work earnings was a special self-contained vertical head fitted with automatic downfeed and a quick return. Fitted with a 5 h.p. motor and gearbox unit, the maximum vertical travel of the quill was 80 mm with 9 rates of feed available from 3 to 50 mm/min. The return rate was set at 400 mm/min and the unit was described as being essential for drilling and boring operation - though the very limited quill travel would have somewhat hammered its usefulness.
A number of suitable-sized rotary, tilting universal and coupled tables were also listed, along with, on machines until the early 1970s, an optical reader system accurate down to 0.01 mm - after which digital read-outs replaced them...

Powered by a 10 h.p. motor held in the bottom of the main column, the drive passed upwards by three V-belts to a 5-shaft speed-change gearbox holding hardened and ground chrome-nickel steel gears lubricated by a pressure pump. Control of the drive was by a single-disc electro-magnetic clutch and a single-disc brake - both claimed to be maintenance and adjustment free.

A useful accessory: Vertical Head Extended Projection. This extended 375 to 525 mm - and consisted of a small right-angle gearbox that clamped around the end of the spindle flange with sets of bevel gears to turn the drive through two right-angles. To add to its usefulness', the assembly could be rotated in each plane through a full 360°

Coxial High-speed Head: an accessory driven by it's own 2-speed, 0.4/0.6 h.p. motor that gave speeds from 2500 to 5000 r.p.m. motor. Obviously intended only for delicate work using very small cutters, this device allowed the miller to be used for such jobs as die sinking and pattern cutting.

Horizontal milling was cater for by the Horizontal Milling Attachment, a bevel-gear driven accessory carried on the spindle end. A most unusual addition was offered for this unit - a second parallel spindle that bolted to the underside and allowed milling cutters of up to 50 mm diameter to be mounted - the device being intended to mill racks and slots.