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Thread: McConnel hedgcutter motor

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    McConnel hedgcutter motor

    I have a McConnel hedgecutter with 1.2 m hard on t flails and am having trouble with it wearing out motors on the head as in they start leaking badly, have fitted new bearings and had it balanced last year, and have the plastic splined collor between the motor and rotor

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    Re: McConnel hedgcutter motor

    Could there be a partial blockage on the return to tank hose? Is there a small third hose on your motor which would be a leak off to return and should eliminate any back pressure? Also,is there a hydraulic return filter and is it clean?

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    Re: McConnel hedgcutter motor

    Has a fleet guard hf6177 can type filter, prob should chance in case this is the problem, only feed and return pipes going to motor!!

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    Re: McConnel hedgcutter motor

    Yes,nothing lost in changing the filter anyway.

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    Re: McConnel hedgcutter motor

    Also this cutter originally had a filter fitted
    i side the tank but I have changed it
    to the can type filter on the return
    pipe to tank!! Is that ok or should it
    be on the feed from tank to pump?

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    Re: McConnel hedgcutter motor

    Quote Originally Posted by case015 View Post
    Also this cutter originally had a filter fitted
    i side the tank but I have changed it
    to the can type filter on the return
    pipe to tank!! Is that ok or should it
    be on the feed from tank to pump?
    The filter in the return line is most likely causing significant backpressure, I have a spearhead machine with the filter in the return line but it has a third pipe from the motor (case drain) to stop the backpressure blowing out the pump seals. Check their isn't a port on your motor to fit a third pipe or else restore it to a free flowing return and be sure the breather isn't trapping pressure in the tank as most high flow motors aren't intended to have a load of pressure on their shaft seals . Even a temporary kink in a badly routed hose or one fitting undersize can blow the seals out of a motor with no case drain. Because of cavitation issues many modern machines use what is effectively a clean tank that the oil goes out of straight to the pump unfiltered, however the design of these systems generally does not draw the oil form the bottom of the tank and utilises a settlement zone in the bottom 1/3 drawing the oil from a point about 1/3 of the way up. You can't mix and match the older inlet filter style systems wit the new clean tank systems. A filter on the feed side after the pump would need to be able to take the full flow and pressure and be unfeasibly large & expensive. A filter on the suction side will have to have a large enough particle size to avoid cavitating the pump and won't provide the same protection as one that could be fitted to the return side with a case drain on the motor. Small hedgecutters have about a 40-50hp system but bigger ones are typically 70-80hp with pump and motor prices that reflect that so decent filtration is a must.

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    Re: McConnel hedgcutter motor


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    Re: McConnel hedgcutter motor


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    Re: McConnel hedgcutter motor

    Quote Originally Posted by case015 View Post


    Looks like a rudimentary guaze suction strain job with possibly a UCC filter on the return like would be in a matbro. Hard to say without seeing inside the tank, there might be filter on the return at all if it's an old model /design. A poorly implemented external return filter will definitely blow out the motor seals on that. Any pictures of what was originally inside the tank, I assume the section attached to the boom is either an electric on off for the rotor or a cable on off or reverse?___with the motor pipes out the back. It's a fairly na´ve picture when you aren't standing beside the machine and there's a lot of pipes clearly left out.

    http://www.horshamhydraulics.com.au/...ic-case-drain/

    Number 5 here applies equally to a gear motor though the financial losses are exponentially greater in a piston motor hence their concentrating on that.

    http://www.machinerylubrication.com/...pment-mistakes

    The vintage of the pictures would be suggestive of the old suction strainer gauze era way of doing things, remember a hedgecutter is an enclosed self contained system and the amount of contamination around will be negligible compared to say something that has QR fittings pulled in and out several times a day so they could have got away with just a fine suction gauze and /or partial flow return filter with a very low bypass pressure. Motors from that era usually don't have the option of a case drain port so you may have little option other than to remove the return filter and go back to the original setup unless you want to buy a more modern motor and fit the case drain line.

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    Re: McConnel hedgcutter motor

    I just saw your second in the tank picture which explains it all, you need to restore the original system and remove the external return filter or else fit a case drain changing to a case drain style motor if as I suspect there is no case drain option on your basic one. If you have lost the original parts note the way the suction filter deliberately doesn't go to the bottom of the tank where any sediment is left to lurk. If the original parts were UCC in origin you should still be able to get them. You may need to replace the entire return line where you broke it to fit the filter if you cannot ensure the fittings are to the original internal bore. The block I referred to in my earlier post looks suspiciously like it might be regenerating some or most of the return to the pump but that's another can of worms, not possible to tell from the picture anyway. Bear in mind any poorly routed return line that kinks during any part of the arm movements will cause a backpressure spike on the motor shaft seal hence why the hoses are usually very tidily clamped to the framework with carefully planned bends.

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    Re: McConnel hedgcutter motor

    Great info!! Thanks for all the help, owning a old
    hedgecutter is a pain as original filters are not available
    or if I was lucky enough to get one into the hundreds
    Whereas the hf6177 fleet can be got for 30 quid

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    Re: McConnel hedgcutter motor

    If you want an economical solution put something like one of these:

    https://www.phoenixhydraulics.co.uk/...tion-Strainers

    in the suction line in the tank on the piece of pipe that lifts out with the wee lid for cleaning purposes, then go to a David Brown breaker and get a secondhand high pressure filter housing from the backend and braze a couple of fittings on to suit the high pressure pipe from the smaller pump on the back for the controls. Fit it somewhere convenient with the two mounting bolts and it will thoroughly clean all your oil every few minutes when it goes through the smaller pump before it reaches the control valves, elements for the DB bowl are reasonably priced and always likely to be available. You could in theory fit the same idea to the main line but the price of the filter housing and elements would be hard to justify on an old machine. The suction Gauze will catch anything above 90 microns and the other one will catch anything else over time. More than adequate.

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