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Crow

Hydraulic drive pump and motor sizing

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Crow    18

Is there any member who can assist me size a system ,and advise on type of motor and pump for  my mission  to  modify my existing drive to hydraulic, please no don't do it etc replys or other comments from people who don't know ,as Itl only move off topic to something everyone thinks they know about .     Thank you ,Nick.

 

 

 

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Tony Brooks    617

If this helps. The ratio of the capacity of pump and motor gives you the reduction ratio for prop sizing. Its been 50 years but I seem to remember we had 1" pumps and 1.5" motors but can't for the life of me remember what those sizes referred to.

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Crow    18

Thanks tony. Well that's a start . Maybe if iWork from my existing prop size back to the motor and pump t might be the way to go. I've just got a drive motor off a small road sweeper front brush set I'll make a start with that . 

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Tony Brooks    617

Unless you fit a thrust bearing on the prop shaft that motor is no good. Few industrial motors are fitted with a bi-directional thrust bearing. I can't see any need for one on a brush motor.

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koukouvagia    97
9 hours ago, Crow said:

Is there any member who can assist me size a system ,and advise on type of motor and pump for  my mission  to  modify my existing drive to hydraulic, please no don't do it etc replys or other comments from people who don't know ,as Itl only move off topic to something everyone thinks they know about .     Thank you ,Nick.

 

 

 

I have a F11 hydraulic pump and motor supplied by ARS Anglian Diesels. It fitted to my butty with the propellor in the ellum.  It is driven by a 1.8 BMC.  The system works perfectly and I can thoroughly recommend it.

 The people to contact sre ARS http://www.arsangliandiesels.co.uk They will be able to give you the exact set up you need for your boat.

 

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Crow    18

Was going to fit prop directly onto motor output shaft  where the rotary brush fitted  it wouldn't know if it had a prop or a brush on  or am I missing something at a very early stage ,I've seen some reedman weed cutter drives that I want to copy or take ideas from

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WotEver    683
10 minutes ago, Crow said:

Was going to fit prop directly onto motor output shaft  where the rotary brush fitted  it wouldn't know if it had a prop or a brush on  or am I missing something...

Looks like it. A brush simply rotates with only a torsional load. A prop rotates and creates thrust either towards or away from the motor; either trying to pull the shaft out of the motor or push it into the motor. 

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Crow    18

Yes your cock on with that I never thought about that . Bit of a rethink 

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Bricksh    8
11 hours ago, Crow said:

Is there any member who can assist me size a system ,and advise on type of motor and pump for  my mission  to  modify my existing drive to hydraulic, please no don't do it etc replys or other comments from people who don't know ,as Itl only move off topic to something everyone thinks they know about .     Thank you ,Nick.

 

 

 

Don't forget about cooling the hydraulic oil, it will get hot very quickly.

For what its worth we have a 125cc/rev pump and 250cc/rev motor giving 2:1 reduction but thats on a barge weighing over 50T, so you can probably half that or even less.

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Crow    18

Thanks.  It's going on  a 25 ft springer , as by the time I've spent 2.5 k on a total rebuild on a Enfield leg that will still be  a 40 year old agricultural money pit  I'd be better to source some nice close tolerance modern items and make my own drive , the amount of good usable items to make it  I'll find in scrapyards and e bay , I'm in no rush  it's just getting to know what I need .im all ears but would have thought my road sweeper  brush drive motors would have  inner and outer thrusts built in the amount of hammer they get , I'll check .

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Tony Brooks    617

You can use that motor if you fit a thrust block on the shaft before attaching the motor. However allowing for the length needed to repack the gland plus the thrust block, plus the half coupling it may extend too far into the boat. if you go down this route you should be able to use much cheaper industrial motors rather than short production run ones with integral thrust bearings.

You may be lucky with your motor and it may have thrust bearings so check. I can't see what on a sweeper brush would cause large and prolonged end thrust on the motor so I would expect ball bearings that can  absorb a small degree of end thrust to be fine in that application, but not yours.

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ditchcrawler    392

The Voac (think I spelt that right have a thrust bearing on their out put shaft that is why they can mount a prop on them when mounted on a butty. I may have the full spec on my back up drive, I will look later. They are positive displacement pumps and motors so the volume the displace in one revolution gives you the ratio Mine is almost 2:1 the motor is about twice the capacity of the pump, but not exactly.

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Crow    18

Thanks Brian.  At least I know to look for pos displacement ,there's many sorts,  it's understanding what's good and bad for my application, but am already getting a start on my apprenticeship on this forum ,at least I now know how to get a ratio and to ensure it's got thrust washers,

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nicknorman    1,971
2 minutes ago, Crow said:

Thanks Brian.  At least I know to look for pos displacement ,there's many sorts,  it's understanding what's good and bad for my application, but am already getting a start on my apprenticeship on this forum ,at least I now know how to get a ratio and to ensure it's got thrust washers,

Well being picky, thrust bearings not thrust washers. There's a big difference!

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Crow    18

This is how I want to make it ,  but without hydraulic steering,the guides on the transom allow motor and prop to be lifted and the whole lot pivots on Plummer bearings, 

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We maintain a couple of similar setups for a customer which use gear pumps/motors. I'd need to look back through our records for what the current motors are (used to be Volvo) but they are fairly expensive (or we're paying too much for them!) and "sensitive" to damage on the shaft seal from fishing line etc which ends up causing contamination of the oil, leading to frequent rebuilds of the motors and pumps. One motor lasted four hours (from new) having picked up something akin to a bit of keep net.

You should really be using bio-degradable hydraulic oil, so with frequent oil changes and repairs be prepared that it could become expensive to maintain.

So if you really want to go down this route, then I'd suggest most of your time needs to be spent designing an effective shield for the motor shaft seal.

As for cooling, the units we maintain don't have any other than the fact the motor is underwater and the engine/pump is mounted at the fore end so there's about 30 foot of pipework (each way) as well.

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adrianh    11

I may be able to help with this re pump flow etc. Use to design/build industrial systems so have plenty of tech knowledge. Have seen a few systems, you can use a fixed displacement pump / motor setup ( cheapest) or variable displacement. Either way it is likely to be more expensive than a standard say PRM setup. 

PM me for contact details

 

 

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adrianh    11

A motor with seals etc suitable for submersion will be very pricy, 1k plus I expect. I have seen Danfoss motors used directly fitted into old wooden rudder. Only last a couple of years until moisture ingress destroys bearings and let's them leak oil into water way. As far as I remember Anglian use an angled Denison piston motor, similar to Voac . Cost 2k ish or more and not easy to get

Edited by adrianh

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ditchcrawler    392
1 hour ago, Crow said:

This is how I want to make it ,  but without hydraulic steering,the guides on the transom allow motor and prop to be lifted and the whole lot pivots on Plummer bearings, 

IMG_3552.JPG

IMG_3553.JPG

IMG_3554.JPG

IMG_3555.JPG

IMG_3556.JPG

IMG_3557.JPG

IMG_3558.JPG

That looks like a Voac pump/motor to me

ars009.jpg

1 hour ago, nicknorman said:

Well being picky, thrust bearings not thrust washers. There's a big difference!

I didn't mention Thrust washers.

ars2004.jpg

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crossley    23

So the plan is to make a hydraulic coupling between your engine, and the input shaft of the enfield drive?  So the reduction and clutch function is being retained? I can't remember, does the enfield have an integral clutch for fwd/astern?  So your going to have to make two adaptor plates, to carry the motors/pumps, two couplings, pipework between the two, a header tank, a relief valve, pressure and return line filters, and possibly a cooler. If you can afford it, it would be best to let a specialist company specify the equipment, and let them take full responsibility for design, installation, flushing and commissioning. Flushing is vital, and cannot repeat cannot, be over stressed. The slightest suspicion of contamination in the system, be it dirt, swarf, water etc, can destroy a pump in seconds. Hydraulics are very reliable, as long as the oil is clean and free of water. It ain't just a matter of coupling a couple of  motors together with flexible hoses!  Make a start by looking at what torque and speed input the enfield drive requires, and find a motor that fits the bill, from makers catalogues. This will give you the required flow, which will allow you to size the driving pump and pipework. Look at Dennison, Parker, Vickers, Bosch hydraulic catalogues for some ideas. Try and keep the working pressure as low as practical, by using large displacement low pressure pumps rather than high pressure low volume pumps. Best of luck. 

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Crow    18

No buddy that's not the plan at all,that z drive will be redundant .in its place will be a steerable drive motor driven of a pump mounted to engine backplate. And as my old tubs only worth 11k tops I'll not be spending a fortune on pumps and motors there's enough stuff on e bay and elsewhere for not a lot of money ,and that's the way I'm going.all I need to know is cc of motor and pump and I think that's all in hand now

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WotEver    683
On 11/09/2017 at 19:53, ditchcrawler said:

I didn't mention Thrust washers

No, the OP did. 

On 11/09/2017 at 18:31, Crow said:

at least I now know how to get a ratio and to ensure it's got thrust washers,

 

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ditchcrawler    392

One of the problems ARS had with underwater mounting was corrosion of the shaft which in turn lead to end seal failure. I think in one case they ground the shaft and then shrunk a stainless sleeve onto it. This was on a butty conversion

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