×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Hydraulic valve query

Hydraulic valve query

Hydraulic valve query

(OP)
Hello all,
I'm converting a 110v SDS drill to hydraulic operation for use underwater.
I have chosen an OMM 8 hyd motor and coupled it to the existing commutator shaft.
The spec is max continuous 16 lpm flowrate with a max working pressure of 140b
I now require a means of controlling the rotation speed of the chuck, by way of altering the hyd flow through the motor. I know there are needle valves available but I would like to utilise something with a roller or push button action that would be easier for my diver to use.
Any ideas?

Many thanks,
Steve Lucas

RE: Hydraulic valve query

1/4 turn ball valve?

RE: Hydraulic valve query

Few random thoughts:

A 1/4 turn ball valve is unlikely to give you much in the way of fine flow control.

Do you know what the tool is going to be paired with by way of a hydraulic supply? In my corner of the business, we work with a mixture of constant flow, constant pressure and "variable everything - whether you want it that way or not" plants - all of which place their own demands on the controls downstream.

Have you asked the divers how they feel about manhandling a tool that's stuck on the end of a pair of half inch hoses - one of them pressurised to 140 bar?

Keep a careful eye on the state of your fluid. You may get quite a bit of seawater ingress through the shaft seal of the motor.

A.

RE: Hydraulic valve query

(OP)
Ted,
Your link to www.csunitec.com/drills/hammer-drills-air-h... displays the tool that I would choose if money were no barrier.
However, a similar product here in England costs over £2000, a not inconsiderable sum you will agree.
The picture shows the drill being controlled by a 'trigger'; Now, whether this is a speed/flow controller or not, I don't know but a mechanism like that is what i'm after.

Kind regards,
Steve

RE: Hydraulic valve query

(OP)
Zeusfaber,
The intended hydraulic supply is via an engine driven hydraulic powerpack, stationed on the bank with approx 20m of 3/8" hoses supplying the tool. Our divers have been working with UHP water to a pressure of 2000b so are familiar with high(ish) pressures. The hoses are covered in layflat protection thus minimising danger through hose rupture.
The drill body will be sealed as much as possible to avoid water ingress but I will certainly be monitoring the condition of the hydraulic oil returning to tank.
Best regards,
Steve

RE: Hydraulic valve query

(OP)
Apologies,
Merry Christmas to you all!!

Kind regards,
Steve

RE: Hydraulic valve query

Steve, firstly, Merry Christmas.

The trigger in the handle moves a spool valve. The operator can 'feather' the trigger to start slowly. Otherwise, the tool is run at full speed. The valve type is open-center. When 'off' flow is bypassed to return.

Ted

RE: Hydraulic valve query

Water ingress is not likely. Hydraulic pressure in the return line will always be higher than the water pressure. It is more likely that if any leak occurs it will be the exit of hydraulic fluid.

Ted

RE: Hydraulic valve query

The variable speed control is a nice feature but we used hammer drills for years with on-off switches before the variable speed feature was introduced.
Have you considered having the surface tender dialling down the speed until the hole is started and then going to full speed?

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Hydraulic valve query

"here in England" implies 3-5 mm of foam neoprene between the operator's fingers and the trigger, so feathering the trigger is going to be harder than it sounds.

If you were to put two spool valves in parallel, with one set to trigger a few millimetres earlier than the other and with its flow throttled through an orifice, you could get some very tidy two-speed control - but that would force a move to closed-centre valves with a compensator package - and your costs and weight would start to get uncomfortable.

A.

RE: Hydraulic valve query

I presume the divers must work in pairs. Have one manage the drill and the other operate the valve. Develope an operating protocol on the surface before doing the underwater drilling task.

Put a T-handle arrangement on the drill motor. Might be better for torque reaction control. A T-handle with a trigger could be made to operate a spool valve if a two-man operation is not desirable.

In my former life I used to design tools like this.

Ted

RE: Hydraulic valve query

Quote (hydtools)

I presume the divers must work in pairs

That's possible (especially since this discussion is happening on the Engineers with Hobbies forum) - but if it's being done in the context of "Diving at Work", then it's more likely that one diver will be working on his own on comms, with the standby sitting in the wind and rain getting bored on the surface.

Torque reaction control is bothering me a bit too - kind of an extension of my worry about how the diver is going to manage the hoses. We don't know what the task is and whether it's something that can be done while solidly weighted onto the bottom - but it might make a good spectator sport, if only there were a little visibility.

A.

RE: Hydraulic valve query

(OP)
Hi Gents,
There will normally just be one diver in the water with the stand-by man ready to go. The comms system would easily allow for voice control orders between diver and surface but I foresee the initial start-up of the drill being the biggest issue where there might be fine tuning of the start and speed control required. I'm beginning to think an on-off flow valve affixed to the drill, with a flow controller at the power pack (adjusted by the dive supervisor) might be the solution.
I am not concerned about the torque reaction as I am only drilling 6-8mm holes in reinforced concrete.
I would hate to see my diver spinning around like windmill sails.
Regards,

RE: Hydraulic valve query

Put a three-port flow control on the drill. When the control is set to zero control flow, all the incoming flow is directed to excess or return port. Connect the motor inlet to the control flow port of the valve. Connect the outlet of the motor to a t-fitting on the excess flow port of the flow control. This gives the drill operator all the control at the drill. He can meter the drill 'on' up to full flow and completely meter it 'off' to full bypass and zero motor flow/speed. The surface command would only need to operate a three-port diverter valve for surface on-off control.

Edit: A two-port valve could be used for on-off by plumbing it between the pressure and return lines.

Ted

RE: Hydraulic valve query

Generally, on the surface, we use both hands to control the direction and position of the tool and to resist the torque.
One finger on the trigger to control the speed is about it.
You may find that the best solution is to have the surface man control both speed and on-off.
How thick are your diver's gloves? The gloves that we wear on the surface at minus 20 degrees make controlling a hammer drill a little clumsy.

Bill
--------------------
"Why not the best?"
Jimmy Carter

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources