For many livestock farms, the shear grab is one attachment that spends more time fitted to the farm handler than any other during the winter months, and provides for the daily needs of stock feeding and silage handling.
Gloucestershire-based attachment manufacturer Albutt produces between 600-800 units a year with capacities from 0.7m3 to 2.5m3 with designs suited to skidsteer, tractor loaders, telehandlers and loading shovels.
Operations director Tom Worthington advises some key points which are important to keep the attachment working and cutting correctly.
"We produce shear grabs across a wide range of sizes, and different options to suit specific farm needs, but the fundamentals of all machines are the same. All grabs must be sharpened correctly and properly lubricated and maintained to prevent any damage or wear to the attachment frame."
Cutting blades
Virtually all manufacturers of shear grabs will use hardened, specific ground knife sections and blades to generate the clean cut required. With normal use, the blades will wear but sharpening must be carried out correctly.
"Since the grab is cutting through dense and heavy material, it uses surprisingly large hydraulic cylinders to exert the cutting force needed. If the blade is blunt or damaged, or the pins are corroded, this force is transferred into the frame of the grab, not the clamp face.
"Sharpening the blades using an angle-grinder heats the cutting edge and removes the temper of the hardened steel. This results in blades which are softer and more prone to wear. Sharpening should be carried out regularly using a hand file on the outside chamfered edge of the blades only."
For users with heavily worn blades, replacements can be fitted through cutting the worn sections from the front grab and welding in replacements.
"We stitch weld the blades in sections so it is possible to cut them out and replace them. This is a more complex process than a bolted design ,but we have found that any bolted assembly used in the position of the cutting blade becomes so corroded due to acidic silage, that they become impossible to remove when replacements are required."
Tine length and wear
Across several manufacturers, grabs are offered with hardened welded tines, or Kverneland-style steel tines for users to use the attachment to pick up bales when loading a mixer.
"Like the cutting blades, the tines will wear as the machine is used, particularly if users are running the attachment on the clamp floor to pick up material. The tine length is important to ensure the cut is correct and each block is cleanly removed from the clamp. Too short and excess material is ripped away, leaving an untidy, and messy clamp face.
"If the tines have worn back more than 50mm, then replacement tips can be welded on to replace the missing material and return the tines to the correct length. These are supplied to fit to the underside of the tine and welded either side.
"Machines with KV style tines which have worn or bent, these can be unbolted and replaced with new. It is important to tighten any tines which are loose to prevent any further damage."
Lubrication and hydraulic cylinders
The combination of the hydraulic cylinders and the front grab pivots can result in up to nine individual pivots on a machine which require greasing and inspecting for wear.
If pins a worn or seized, then the grab can cut off centre which can introduce large twisting forces to the implement which can have a significant impact and permanently bend the frame.
"The moving parts of the machine must be kept lubricated to provide the maximum cutting performance. All of our pivots are greased and use a helical cut to force the grease across the pins. Replacement of any worn pins and bushes prevents minor issues from creating a more serious impact on the overall grab."
Depending on the machine size, two or three hydraulic cylinders are used to power the cutting blade.
"Any damage from miss-use or corrosion due to the long-term impacts of acidic silage on the cylinders and rods can cause the pistons to leak. This can be solved by resealing or replacing the entire piston, which improves the cutting performance and prevents any oil contamination into the feed."
