Digger quick hitch

[fermerboy]

Just bought a second-hand quick hitch for my New Holland backactor, just saw it at collective sale and thought it would be handy.
What are the rules regarding these now?
I know there were changes but not the detail.
This machine will only ever be used on farm for our own drainage and ditching jobs.
Are there do and don'ts for plumbing it in?

 

[Lincs Lass]

Back in 2008 I had to do a quick hitch test ,this was because a guy at drax power station was killed after a bucket on a back actor dropped on him ,,the machine had an hydraulic latch but the operator didn't put the locking pin in and the latch creeped open and the bucket fell on the guy ,,at the time I was on a 360 with a dramone auto hitch ,,we were all told that just because the hydraulics were isolated ,it didn't prevent the latch opening and anybody on site that didnt put the safety pin through ,would be off site

 

[Zetor]

The latch on a hydraulic Qhitch is designed to be under constant hydraulic pressure to keep it closed usually piped directly to the output of the hydraulic pump (via two way valve) hence why you normally have to crowd/deadend the bucket ram to build pressure in the system to activate the Qhitch.

 

[Lincs Lass]

Both Daewoo and volvo used to have a switch to operate the auto hitch ,,when activated you just crowded the bucket to release the latch ,change and then crowd again to engage the latch ,then switch to isolate the oil flow but without the safety pin ,the locking latch could still creap open .
This is why small hire 360s do not have hydraulic hitches ,only manual versions ,it stops the chance of an accident

 

[Zetor]

Both Daewoo and volvo used to have a switch to operate the auto hitch ,,when activated you just crowded the bucket to release the latch ,change and then crowd again to engage the latch ,then switch to isolate the oil flow but without the safety pin ,the locking latch could still creap open .
This is why small hire 360s do not have hydraulic hitches ,only manual versions ,it stops the chance of an accident

Oil flow to the hitch is never isolated it’s always under a constant feed to keep it closed.

 

[jd6820]

Two types of hydraulic hitches available. It depends which type you've purchased but both are safe if operated correctly.

Semi automatic hitch: Operates the bucket latch hydraulically. Usually a fixed front jaw and a moving rear jaw, no means of locking the front bucket pin into the hitch. Therefore as an extra safety item a locking pin is fitted to prevent the rear jaw moving and releasing the bucket in the event of hydraulic failure. Although good this isn't generally as safe as a twin lock hitch because the front pin isn't retained so you can pick up the bucket, miss latching the rear pin and crowd leaving the bucket liable to drop off. You'd have to be pretty in competent for this to occur.

Twin Lock or Fully Automatic hitch. Often use a combination of devices to lock the rear jaw from opening unless activated by operator in the fully crowded (safe) position and they also retain the front pin so the bucket although only retained on the front pin won't drop off accidentally. A much safer design and therefore this industry adopted standard. Not infallible though!

 

[Lincs Lass]

Oil flow to the hitch is never isolated it’s always under a constant feed to keep it closed.

Like I said ,,,Used to ,,over the years newer and safer locking systems have been made ,,the new volvos on the site back of me dont have to use a pin ,just swap buckets and carry on .

 

[cousinjack]

Isnt there also something about a locking claw on the front pin ??
Our first quick hitches didn't have these, so they had to be changed for ones with it..

So that even if the rear pin slips out, the front still cannot escape and let the bucket fall ...

 

[cousinjack]

@jd6820 beat me to it again !

 

[jd6820]

Oil flow to the hitch is never isolated it’s always under a constant feed to keep it closed.

Yeah, that's spot on. To clarify all that occurs when you rock the switch and dead end the crowd cylinder is two things, the safety is released either a gravity latch (Volvo)/check valves or a pressure switch to allow hitch ram movement. Then pressure gets diverted by hitch valve to the other side of the ram to open it. Once the switch is released or turned off the oil then gets diverted to close the ram. This close action is happening most of the time the machine is running. To clarify this I mean when the pump is providing hydraulic pressure. This is usually on bigger and more modern machines when a service is used. The hitch valve getting its supply usually from the pump supplying the bucket crowd action, so when you move the bucket lever the hitch is constantly being tightened.

Old or new systems operate using this method. The reason for the safety pin on early hitches is mainly for the times the excavator is left idle or switched off. This on a leaking hitch cylinder allowed the rear jaw to creep, a dangerous circumstance were you not expecting it. Say you picked the bucket up having parked up to help couple a pipe in the trench then swung over the trench with your unlatched bucket... That's how accidents occur.

 

[Zetor]

Like I said ,,,Used to ,,over the years newer and safer locking systems have been made ,,the new volvos on the site back of me dont have to use a pin ,just swap buckets and carry on .

Theres various different locking systems, my 2002 JS130 relies on the safety pin just like you mentioned but my 2006 JS130, CX130 & my EC140 have a double lock system a there’s a spring inside the ram and a second lock that works on the position of the Qhitch, my TB290 & TB230 locks both pins but they ALL rely on a constant hydraulic pressure to keep the bucket on, everything else is failsafe, I don’t want the OP to connect it to the digger aux (like a telehandler Qhitch) as it would be dangerous.

 

[fermerboy]

Thanks for the replies.
Its a Miller quick hitch, with one small double acting ram.
It has a fixed jaw that would slide over the dipper/pivot pin and the hydraulics grip the "ram" or outer pin.
There appears to be a hole to take a safety pin preventing the jaw opening too.
I do understand that it needs to have hydraulic pressure gripping the pin all the time, thats no issue.
I wasnt too sure what the changes were regarding the safety locks etc.
Will need to have a look at a NH with a hitch to see how its plumbed in now.

 

[Bloders]

My understanding is semi automatic hitches are not allowed.
Either manual hitch (get out, use a bar and release the bucket etc) or a fully automatic hitch - hydraulically operated but no "ocking pin" required.
My understanding also is that you are not allowed to sell semi automatic ones, though as most things, i dont think there is anything to preevent using one already in use, if that makes sense.

 

[Zebbedee]

My understanding is semi automatic hitches are not allowed.
Either manual hitch (get out, use a bar and release the bucket etc) or a fully automatic hitch - hydraulically operated but no "ocking pin" required.
My understanding also is that you are not allowed to sell semi automatic ones, though as most things, i dont think there is anything to preevent using one already in use, if that makes sense.

As far as I am aware there is no law regarding quick hitches but there are safety guidelines, most construction sites will not allow hitches on site that require a safety pin but they are not outlawed by law, HSE website has more info and tips regarding use of hitches whenever I swap a bucket I turn the bucket on the ground trying to lift the machine which ensures it is actually attached as per hse suggestion quick easy and practical then always ensure personnel in vicinity of machine are never under or close to the bucket