reel not working

[MShineV]

Hello evverybody,
at one of our machines, that we designed, we are using a twin hose reel to suply a twin hydraulic hose to a moving hydraulic cylinder. The reel is backwindet by an in build leaf spring. About a meter below the reel the hose is twisted by 90 degrees in axial direction and fed through a puley (the hose is now runing parallel to the rotational axis of the reel). The operating pressure is 130 bar and the hose diameter is 1/4''.
The reel we bought is designet to work with hydraulic hoses.

The problem is that, the reel didn't wind in the hose when we tested it on the finished prototype a few months ago (the hose was under pressure).After that we hawe taken the machine apart. Now we have tried to make the reel work and suprise it does, without modifying anything (but without the pressure, the machune is still taken apart).

Is the pressure+twist the culprit, or is something happening with the leafe spring, or something else? Any ideas?

Thanks alot.

 

[desertfox]

Hi

Well you have access to drawings, materials, dimensions etc.
Now please read your post and pretend that you know nothing about the system you've described and then consider how we could possibly answer the question.

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

 

[Jboggs]

You made no mention of any contact with the manufacturer of the reel. In my opinion they are the only ones that can answer your question.

 

[BrianE22]

Maybe the pressurized hoses are stiffer and harder to bend?

 

[moon161]

http://www.efunda.com/designstandards/sensors/bourdon_tubes/bourdon_intro.cfm

http://eprints.lib.hokudai.ac.jp/dspace/bitstream/2115/23411/1/21(1)_P12-26.pdf

 

[dhengr]

MShineV:
Check to see if someone added Viagra to the hydraulic fluid. Then change the leaf spring to a coiled spring. And, if those fail, call the manufacturer of the reel. They will probably need your hose layout drawing to make any sense out of the problem.

 

[berkshire]

Have you checked the return wind tension on the reel ? you may not have enough pre-wind on it.
B.E.

You are judged not by what you know, but by what you can do.

 

[MikeHalloran]

Pressure could indeed make all the difference.
The extra twist doesn't help. See "Corvair fan belt problems".



Mike Halloran
Pembroke Pines, FL, USA

 

[tbuelna]

The problem may be with the construction of your hydraulic hose and how the end fittings are attached. High pressure hoses often have multiple braided fabric reinforcements that don't like to be twisted.

 

[Strong]

In addition to the hose being stiffer and resisting the shape change going from straight to curved on the reel, have you considered possible higher friction at the rotating joint fluid seal?

Walt