An innovative design for a rope clutch – but will it catch on? We’re all familiar with the usual lever and jaw clamp style of rope clutch, but recently there has been a few innovations in this market, the Karver Jammer being one of the more unusual. This innovative design uses a completely different principle to most existing rope clutches. Instead of ‘crushing’ the line between two opposing flat or vee-shaped jaws, the Karver’s mechanism resembles the jaws of a drill chuck, gripping the line firmly from three sides. This results in greatly increased overall holding power and almost a complete absence of slippage. The design is also likely to inflict much less wear on the line than any of the two-sided devices as less pressure is required to hold the line due to the increased surface area of the jaws.

The KJ10: easy to install and powerful, but expensive

Despite this clutch receiving a Special Mention in the 2013 DAME awards at METS, we feel it rather suffers from ‘style over substance’ syndrome. To lock the jaws open and thread the line you pull on a small bar connected at each end via wire to the clutch. We tried the 10mm line diameter model, which will take a braided line up to exactly that – not a micron more. Even burned-off ends are enough to stop the line from being inserted.
Then to engage the clutch you have to pull on a tiny, T-shaped plastic handle attached to the clutch by two 1mm diameter cords. It’s just far too fiddly and difficult to operate, and even more so with cold or gloved fingers. It also won’t release under a load greater than 100kg and we all felt 
it wouldn’t be long before the dangly knob on string gets ripped off, rendering it useless.

The ‘drill chuck’ design increases holding power and reduces wear

It looks well made from smart anodised aluminium and it is easy to install and disassemble. But it’s quite wide (50mm) and only available as a single clutch. Verdict: Innovative and well-engineered, but moderately impractical and frighteningly expensive. It has superb holding power and slippage control, though, if that’s what matters to you.
Price £234.00  Contact Allspars Ltd Tel 01752 266766 www.allspars.co.uk