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Hydraulic Motor Options

03/13/2017 12:27 PM

My son is putting together a dredge for clearing the silt from his boat slip. He wants to build an auger head and power it with a hydraulic motor. He already has the hydraulic power unit. There are hydraulic motors marketed specifically for dredge auger heads. However, they are quite more expensive than off-the-shelf units that he can buy. He was told by the dredge hydraulic motors sellers that their motors are specifically made to work under water in order to keep water and silt out. I would assume that any hydraulic motor, which is built to keep hydraulic fluid under high pressure inside the unit, will keep the water and silt out. Am I missing something?

Thanks,

Don

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#1

Re: Hydraulic Motor Options

03/13/2017 12:32 PM

Yes. The design of the hydraulic motors will (most likely) have 2 seals - 1 for keeping hydraulic fluid in, and 1 for keeping water from getting into the motor.

Just my 2¢

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#3
In reply to #1

Re: Hydraulic Motor Options

03/13/2017 1:06 PM

Thanks Kilo.

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#18
In reply to #1

Re: Hydraulic Motor Options

03/14/2017 8:28 AM

and silt under the sealing surface

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#2

Re: Hydraulic Motor Options

03/13/2017 12:36 PM

How much use will he get out of this dredging unit?

And out of curiosity,... how big a hydraulic motor is he looking at?

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#4
In reply to #2

Re: Hydraulic Motor Options

03/13/2017 1:16 PM

And may we ask, how large is this boat slip? 500' x 100'? How deep is the draft of his boat?

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#6
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Re: Hydraulic Motor Options

03/13/2017 1:38 PM

The slip is about 20ft X 30ft but the silt builds up another 40 ft out in the river. And, under current state regulations, the silt can't be discharged back into the river. We use a dewatering bag and also discharge in another area lined by silt fencing.

Not sure what the boat draft is.....I guess 16-18 inches. Unfortunately, the river level changes considerably. If we don't get rain for a couple of weeks, the river level may drop 2 or 3 feet.

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#5
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Re: Hydraulic Motor Options

03/13/2017 1:26 PM

I'm guessing he will be using the dredge at least twice a year and each use would be for about 16 -18 hours. And, if I can't get my local government to clean the canal behind my house, I may put at least that much time on it.

I'm not sure what size hydraulic motor he is considering. I believe the hydraulic power unit he uses puts out 10 gpm. But he currently uses it to power the hydraulic pump, about 6 gpm, used to discharge the silt and water. He is using a 300 gpm, gasoline powered, trash/water pump to kick up the silt which the hydraulic pump picks up and discharges. It works pretty well but it takes a lot longer if clay is encountered. And, it doesn't do much at all on sunken branches and logs.

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#7

Re: Hydraulic Motor Options

03/13/2017 1:44 PM

Staffa make a hydraulic motor which is sealed against water ingress.

I’ll warn you now, they are not cheap.

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#8

Re: Hydraulic Motor Options

03/13/2017 1:48 PM

This looks pretty cool......

http://www.diy-dredge.com/

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#9
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Re: Hydraulic Motor Options

03/13/2017 2:03 PM

So... use a weed whacker and convert the leaf blower to a silt thrower? That actually sort of makes sense.

What do you do about trees, carcasses, etc.?

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#15
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Re: Hydraulic Motor Options

03/13/2017 3:40 PM

"What do you do about trees, carcasses, etc.?"

Wait till they become silt...?

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#10
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Re: Hydraulic Motor Options

03/13/2017 2:10 PM

That looks like an agricultural manure slurry pump

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#11
In reply to #10

Re: Hydraulic Motor Options

03/13/2017 2:25 PM

Hey buddy, watch where you're aiming that thing!

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#12
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Re: Hydraulic Motor Options

03/13/2017 2:36 PM

Metaphorically speaking, it kinda reminds one of the political rants in the break room,... doesn't it?

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#14
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Re: Hydraulic Motor Options

03/13/2017 2:50 PM

Who slings the most in the widest swath is the winner?

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#13

Re: Hydraulic Motor Options

03/13/2017 2:38 PM

Rust comes to mind as the biggest issue. Not all off the shelf hydraulic motors are designed to be submerged. Shaft composition to keep it from rusting. A rusted shaft will destroy and seal.

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#16

Re: Hydraulic Motor Options

03/13/2017 6:52 PM

I'm not following the concept of what the hydraulic motor and auger is doing out under the water if there is already a large trash pump silt removal system (hose based collection and discharge?) in use now.

A 2" - 3" trash pulp with a jet head (underwater vacuum cleaner head with water jets to break up the silt as it suck s it in) silt collection system will move a lot more silt than a auger system ever will and it will do it way safer too.

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#19
In reply to #16

Re: Hydraulic Motor Options

03/14/2017 12:42 PM

The current system uses a gasoline trash pump which suctions water from the river and discharges the water beneath the hydraulic suction pump. The trash pump discharge, 300gpm, breaks up compacted silt, leaves, etc. The hydraulic pump then picks up the "stuff" and discharges on land via a 4 inch hose. This system works effectively except when clay, branches, logs, etc. are encountered which happens often. The auger will work better than a water jet to break up the more compacted and harder stuff encountered. It is basically what is used on a larger scale on the Mississippi River and other larger rivers. The auger, which we will build, will probably be about 3 to 4 feet wide.

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#20
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Re: Hydraulic Motor Options

03/14/2017 4:10 PM

That sir, is a large auger. I hope you have good success with it!

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#21
In reply to #20

Re: Hydraulic Motor Options

03/15/2017 12:54 PM

James,

Sorry, I didn't explain the auger well. The auger will probably be about 6 inches in diameter and about 3-4 feet long. The 3-4 ft length of the auger will be laid down horizontally, not vertically. So, the auger will be clearing a 3-4 ft wide, and 6 inch deep swath.

As the auger spins it moves the spoils toward the center (the auger will be split into 2 sections, left and right) where the suction pump picks up the spoils and then pumps them out through the 4 inch discharge hose.

I hope this explanation is, at least, "clear as mud".

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#17

Re: Hydraulic Motor Options

03/14/2017 8:24 AM

Don,

most of these designs put the drive unit at the front. as this is a somewhat limited use application, put the motor up in the dry and pull the belt upwards. the motor will stay "DRY" and you don't need to worry about the dual seal assembly. as for motors, WHITE, PARKER, CHAR-LYN are all good reliable units. also, any Farm Store should have hydraulic motors for silage and conveyor use.

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Don Blashka (1); Don in LA (5); James Stewart (5); Kilowatt0 (1); ozzb (1); phoenix911 (3); rwilliams (1); SolarEagle (2); tcmtech (1); TonyS (1)

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