sheargrab problem

1chippy

we have a sheargrab, rear mounted thats not cutting the blocks clean. it seem to tear more than cut. one side seems to pull more than the other and as i am closing it down it seems to lift more to one side. The knives were replaced and have been sharpened stil to no avail. The tines would be slightly worn but nothing more than what seems to be normal on grabs i have looked at that seem to be cutting ok.
I know to some this may sound petty but i am trying to keep a clean pit face and this is just not working. Would it be worth replacing the head of the grab completly or what sort of cost does anyone know. we had a few lads try and sort the old one but just doesnt seem right.

Odelay

Does it have one cylinder or two? If two then one maybe "PASSING" may need a new internal seal. hence lopsided cutting?

blue5000

Chippy it could be due to a few things;
stemmy silage,
temper gone in blades, happens when they are sharpened with an angle grinder,
bad hydraulic pump.

Is it the crocodile teeth blades or straight blade?

pakalasa

Odelay wrote: »

Does it have one cylinder or two? If two then one maybe "PASSING" may need a new internal seal. hence lopsided cutting?

This could be it. Swap over the cylinders from one side to the other. See if the problem goes with it.

49801

ours was tearing something silly the last 2 years.
Got the tines replaced and is cutting like new.

try swapping the rams as suggested but after that i'd say its definitely the tines. when the tines are worn its like using a scissors that is not tighten properly.

funny man

What way do you cut your blocks out of the pit. Do you start on the same side and work your away across one block at a time or do you take every second one and then take the ones in between.

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freedominacup

funny man wrote: »

What way do you cut your blocks out of the pit. Do you start on the same side and work your away across one block at a time or do you take every second one and then take the ones in between.

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Second one keeps the wear and pressure even.

Muckit

I think 49801 could have hit the nail on the head.

What does the pit face look like when you take out a block 1chippy? A small sliced through layer on top with a big hole underneath? If so it's def the tines. It's the tips of the tines that give the equal but opposite force back that is needed as the front blades try to slice down through the silage. As the tips are worn back from the blade, the forces don't line up. When the blade has no force pushing directly back on it, it stops going down and the bottom of the grab, the tines, start moving upwards creating the hole.

I like the scissors analogy used by a previous poster. If any little gap, paper will turn rather than cut. Same with a hedge clippers.

I would at least replace every second cranked tine for the time being and you should notice an improvement. Ideally replace all cranked tines. Outside straight tines should not be worn as they don't drag on the slab as you take out the bottom blocks.



Another small but important thing to keep right are the two little nibs each side of the front of the blade that keeps the blades up off the concrete when grab is closed fully. They should be kept pointy. When taking out the bottom blocks, close the grab fully, then once the block is cut, open the grab slightly before pulling out. This stops them dragging on concrete slab and again at shed when you drop it down.


Taking every second block out is also a very good idea, even though I don't do it myself!

1chippy

twin rams on the grab. i'll change them over the weekend. the tines, i'll change every second one for now. i'll have a great collection of podge bars soon.

Odelay

1chippy wrote: »

twin rams on the grab. i'll change them over the weekend. the tines, i'll change every second one for now. i'll have a great collection of podge bars soon.

If it's not that then you will have to wiggle the linkages with one of them many spare podge bars you will have!
If there is play on one side then that could be it if there is play on both sides then time to get the wallet out. Play on one or both side is not how the grab operated on day-on. The play might seem even but the hydraulics won't think so and will favour the easier side.

blue5000

1chippy wrote: »

twin rams on the grab. i'll change them over the weekend. the tines, i'll change every second one for now. i'll have a great collection of podge bars soon.

Hi chippy did you ever get this sorted, does it work any better?