It depends on which STV you have. First, let's assume it is the smallest because this would give you the most limited choice. The 32hp STV32 weighs a little less than 1,000kg and gives you quite a few options because these days you don't have to have a big tractor to take advantage of a big mower - even if you want to continue providing a cylinder-mower finish.
There are a few gang mowers that will match the STV32 but you are unlikely to gain much in terms of cutting width - perhaps 20cm depending on which triples you were using. Sisis Equipment of Macclesfield offers several three-gang units for small compacts, including the 2.13m HD84 and TR84.
Alternatively, the Leda Trio ground-wheel driven set from Lloyds will give a 2.08m cut. A small compact tractor can cope with this three-gang mower, as could the Ransomes trailed units. If you want something more sophisticated, Ransomes' Mounted 214 may fit the bill but it is still only a three-gang with a 2.14m cutting width - though it will cut 1.5ha/h (3.5acres/h) at a speed of 10kmph (5mph).
For greater output from a cylinder gang, you need to be looking at five-unit kit. Sisis's HD138TR will give a 3.5m cut and can be used with Kubota's middle-of-the-range 35.9hp STV36. The Lloyds Leda Quintuple and Ransomes trailed five-gang (both cutting a 3.5m swathe) would work with the largest STV - the 39.5hp STV40. For hydraulic gangs, you would need a bigger tractor.
If you have the STV32 or STV36 and want a significant gain in cutting width and productivity over your triples, I suggest you take a look at rotaries. Cutting quality and final presentation from a rotary are much improved. With the option to mulch (assuming you have time for fairly regularly mowing), today's rotary mowers can leave the sward looking clean and the choice of machines with rollers means that grass can be striped for that extra-manicured look.
While there is a good choice of 1.8m rotaries for 30-something horsepower tractors - including finishing and roller mowers from Muratori (distributor AJ & R Scambler), Reco SGG, Teagle, Tomlin and Wessex - you should look at the 8400GR Rollermower from Major Equipment. It gives a 2.43m working width and should be fine on the STV32.
If you have the series-topper STV40 you could consider wider rotaries, such as the 2.4m Wessex Proline from Broadwood - a British-built rollermower that impressed our testers with its speed, strength of construction and quality finish (HW, 3 July 2009).
But there is a bigger machine that could work with the smallest STV tractor. With a massive 3.65m cutting width, the Progressive TDR-12 roller mower has just been introduced into the UK by The Grass Group and I am told that it only requires a compact of 30hp.
I can't wait for a chance to see this machine in action. Whereas other roller mowers suited to compact tractors are of a fixed-deck format, this one has three floating decks. This machine should also be good on undulating ground and it is said to have the ability to cut as low as 13mm without scalping.
- Sally Drury has reported for HW and its forerunner GC&HTJ for 27 years and has spent more than five years testing machinery for HW and What Kit? The advice in this helpline is independent.