Winch Design Rules of Thumb 5

[Losty]

Are there any rules of thumb for drum, flanges and drive shaft design of a winch.

Known quantities are:

Line pull
Rope/Wire diameter and length
Operating speed

Any reference online or book specially on winch design would be helpful!


Thanks in advance

Losty

 

[Philrock]

There are many such rules. The U.S. Steel Tiger Brand Wire Rope Hand Book is a fabulous reference. It is also probably out of print and very difficult to obtain. You might try Ebay, used book sellers, and libraries. Machinery's Handbook is also pretty good, as are many manufacturers' catalogs. For shaft design, use the Westinghouse or ASME shaft code.

http://www.baymachinedesign.com

 

[arto]

Blodgett's Design of Weldments has a section on the drums:

https://ssl.lincolnelectric.com/foundation/

 

[deanc]

For links:

http://www.martindalecenter.com

 

[deanc]

Oh yes: Large site and a very good one.

Go to Calculators on Line,then,Engineering:A-Z

 

[whotmewory]

Hey Losty:

Your subect sure struck a sentimental chord with me.

I was the Winch Product Engineer with Ingersoll-Rand's Seattle Winch and High Capacity Hoist folks during the nineties.

Before concerning yourself with design stresses [drum hoop stresses and foundation bolting stresses] and gearbox design and the like, make sure you understand your customer's linespeed and load capcity correctly.

Is linespeed at the top layer, middle layer or first layer? Same for the load, is it first layer load or top layer load. These come into greater play with lifting than with pulling. For hoisting, as the wire rope accumulates on the drum, load capacity drops as torque rises.

What size wire rope does he prefer or are you specifying the rope? If so, choose a rope at 3:1-to-5:1 safety factor.

If your customer wants to LIFT PEOPLE, the winch must meet ANSI Man-Rider design minimum requirements, and standard winches used for this purpose will only get you sued into the poor house.

At IR we designed for a five to one design safety factor because winches are also using to raise and lower {as drum hoists} as well as pull (rail yard cars) and the material handling institute (MHI) specs five to one for overhead applications>

From a structural design point of view< drum hoop stress is important and your frame _ especially where you"re going to bolt down at _ is important (if this looks funny< it"s because my keyboard is acting weird)>

What is most important is your braking devices: pulling winches may have either or both a disc brake and a drum band brake while drum hoists (raising and lowering) are usually required to have both disc and band brakes>

I hope this is some food for thought.

chris in NC

 

[Losty]

Thanks guys for your prompt replies....

I am totally new to this subject of winch design...i got some insight, enough to take my fisrt step.
However, it will be great if there are any books dedicated to this subject and explains how to go about designing winches.

And also Chris, thanks to you for your opinion. I would really appreciate if you can share your experience with us on this subject.

As you mentioned, lets assume some hypothetical data:

Application - Man lifitng winch
MAX LINE PULL - 4 Tonnes
Line speed - 70-100 m/min
Rope size - 18 mm

If you have the above info , how would you go about designing a winch?

THanks in advance

Losty

 

[GregLocock]

Chris - is there a standard solution for the pressure on the drum as the number of layers increases?

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[whotmewory]

Greg:

Actually we did some FEA on some drums and found that presumed beliefs about structural loading on the drum and on the side flanges were not necessarily true.

For example (1) presumptions about the side flanges witnessing the greatest pressure at the base where they met the drum, and (2) drum pressure increasing with layers of wire rope.

As I recall, our Finite Element Analyses (FEA)revealed:

(1) that pressure on the flanges existed as a "band" a few inches wide at just about the middle of the flange. So for an 8-inch flange, say, the "band" of exerted pressure might be (and be aware I'm relying on memory) a circumfrential band about 1-2 inches wide at about 2-3 inches from the drum surface...

And (2) that the pressure on the drum increased with layers till about half full. After that, the dynamics of the rope scrubbing against itself seemed to level off the pressure exerted on the drum. In other words, what was happening was the lower layers' friction was preventing the upper layers from constricting any further (like a Python) on the drum.

What we did find was that the "pulling" effects on the welds at the base of the flanges where they met the drum saw some fairly high tensile stresses - as the flanges were "pushed out" and the drum conpressed - but still well within our 5:1 design safety factors.

I'd have to check my notews before answering you on determining the pressure on the drum to use for your hoop stress calculations.

Chris

 

[whotmewory]

Losty:

Since you are designing a Man-Rider winch, BEFORE I'd even start any math, I would find out:

A - What are my customer's corporate engineering standards - if they have any - that govern drum hoists used to lift and lower people. Some companies - especially oil companies - go to great lengths establishing rather meticulous but well written standards governing equipment used on their facilities.

B - What national or regional standards for safety govern personnel safety equipment. For instance - in the US, the US Code of Federal Regulations (CFRs), ANSI, American Bureau of shipping (ABS). In Europe it might be the Machinery Directive, Llyods, or Det-Norske-Veritas.

C - What industry standards - for example - the Material Handling Institute (MHI) - perhaps govern my application.

Any or all of these standards will certainly steer your math.

There are no books that I know of dedicated to winch design. But you can visit the websites of various winch manufacturers (JeaMar, Superwinch, IR, Clark, Womack and others) to at least see what you're competing against.

There's not at all a lot of money in making winches unless they are specially designed turn-key packages. There are simply too many hungry competiitors on the market offering your basic turning drum.

Versatility is a good feature, low noice level and ergonomically friendly can put you ahead, but probably your best tool against the competition is short order-to-ship time frames and GREAT follow-up customer support and parts service with damned good manuals easy to read and INEXPENSIVE repair parts.

There are some parasitic aftermarket repair companies out there killing the OEMS by fixing and refurbishing for resale a lot of OEM's own equipment. You need to think like them and protect your product line.

Go get 'em!

Gott'a get to work...

Have a great weekend!

Cheers!

 

[Philrock]

While a drum for a hoist is technically a winch, it has been my experience that a piece of equipment called a winch has a much smaller drum diameter relative to the cable size.

For example, we’ve all seen winches on the front of pick-up trucks with 1/4” diameter wire rope and a drum diameter of about 4”. Assuming the rope is 7 x 19, this puts the ratio of drum diameter to wire (not cable) diameter at about 250. The U.S. Steel Wire Rope Engineering handbook recommends a ratio of 900 for elevators. This would put the drum diameter at almost 15”.

You should consider whether or not to use a spiral grooved drum. If not, be sure to wind the rope on the drum in such a manner as to make consecutive coils hug together. For a right hand lay rope (which is standard) this is done by wrapping the rope in a left hand helix – i.e. after the rope is wound on the drum it looks like a left hand thread.

Making a man-lift is a Big Deal. Lots of regulations. Controls will be a significant issue. It would probably be well worth while to hire an elevator consultant to keep you on the straight and narrow. Hope you’re making enough of these to make it all worthwhile.

 

[GregLocock]

Thanks Chris, I was involved in winching a cable that had a different (softer) radial stiffness to axial stiffness. This meant that the additional wraps tended to compress the inner layers, reducing their tension. Off hand I think we found that the pressure on the drum stopped increasing after 7 layers. We also measured the side load on the flanges, but I cannot remember the conclusion there.

One important parameter is the friction of the cable, if it can freely slide over itself then the drum pressure will build very rapidly.



Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[Losty]

One again many think to you guys for your time in providing me enough infor to make a start....

Just a quick question on the braking systems for a man-rider winch...As mentioned by Chris there that IR winches have a disc and drum brake mechanism on the man-ridere winchs.

Can you explain how and when these two different mechanism are used ...i mean in what situation (such as to begin the rotation of drum, emergency etc.) and how they are activated (manually, hydraulically) etc.

Thanks in advance
Losty

 

[Losty]

Bit more clarification on my previous post, are the two braking mechanism (band abd disc) on the main drum independent? ..and how they are activated in what circumstances.

Losty

 

[whotmewory]

The valving to your winch design should work such that air or oil to your [air or hydraulic] motor should be provided BEFORE [air or oil reaches and releases] the band or disc brakes, otherwise [when hoisting or pulling up a slope] you can have an "overrunning load" in which - should your brakes be released BEFORE your motor inlet ports are FULLY pressurized - your load could "runaway" and your motor shaft sheared as your motor tries to control and stop the "runaway" load. Don't count on the disc brake always stopping the runaway load. there's a lot of powerful and potentially catastrophic dynamics in runaway loads.

For hydraulic winches SUN Hydraulics and Compact Controls are both very high quality sources of cartridge valves for your motor controls manifold - which should be mounted at the motor ports - not at some distance - as distance can defeat the sensitivity of your counterbalance and motor sequencing controls. I prefer S"UN for their customer responsiveness.

Air winch motors can be overrun, so be sure your [air winch] customer or application actually calls for or rejects this characteristic. Matter of fact, some customers actually want this: this use it as a type of load moving "control."

Gott'a go.

Cheers!