One of two new grabs announced by Kinshofer is ‘the biggest change in clamshell design since the introduction of clamshells,’ according to Kinshofer UK director Ray Rhind. Kinshofer has been manufacturing grabs for more than 30 years. Clamshell grabs have previously been operated by hydraulic cylinders which are susceptible to damage in use, particularly if while the grab is open it is dropped or powered down onto a rock, for example.

The difference with the new Compact Drive K6 clamshell from Kinshofer Greiftechnik GmbH is that it does not use hydraulic cylinders. Instead it has an integrated drive hub, running in oil. In addition to not having vulnerable hydraulic cylinders the new design has further benefits. Conventional clamshells, due to their geometry have the majority of their opening and closing force at the extremes of the travel or stroke and the power drops off towards the centre of the stroke or travel range. The integrated hub of the new K6 has a constant closing force all the way through the stroke.

The maintenance demand of conventional clamshell grabs is high, Rhind says, typically with several grease nipples on the pivot points that require regular attention. The K6 has a single grease nipple, and that is on the rotator head and not the grab itself.

The pre-production version of the K6 shown at the UK’s Commercial Vehicle show in May has on top of the rotator some exposed metal hydraulic piping to feed the rotator that will, on later versions, be fed straight into the hub through the centre of the shaft with no external piping.

Another advantage of the new grab, according to Ray Rhind is that different sized shells can be fitted to the same operating hub for different applications so only different sized shells are needed instead of the whole grab.

The new K6 grab without hydraulic cylinders is to be launched at the IAA show, Hannover in September. Its initial purchase price carries a premium of between 12% and 15% over conventional grabs but this will be easily recovered in less than a year, Rhind claims, because there is so much less downtime and maintenance cost.

The second new Kinshofer grab is the KM 331 Compact, claimed to be the most powerful scissor grab on the market. It is light, has a low profile and the specially designed legs mean that only the minimum amount of space is needed between packs for the legs to get in. There is a twin pin retention system for the rails to give better performance.