Cable Brake

[BruceWard]

I am looking for a some kind of brake to use on 5/16" cable. I need to brake a load going down hill on the cable. Can anyone suggest a brake solution?

Thanks

 

[PILOON]

If the load is being held back by the cable and the cable long enough you could always let gravity do its job by doubling it back to the bottom and attaching it to your tractor and then you drive up letting gravity take the load down. Naturally you need a pully or a tree for which to to double the cable around.

Another method could be to attach an old wheel to your tractor draw bar (bolted so as it does not turn) and if the load is within reason 2 or three wraps around the wheel being held using gloves you could just let it slip its way down.
It is amazing how much of a load a pair of hands can hold back with that kind of friction a few wraps can provide.

If a tree were handy, about 3 turns would act as a super brake.

I once rolled a 1000 lb steel H-beam into place by simply wrapping 3 turns around a trailer hitch and just eased off rope as needed.
We used steel rollers on a 'trail' of overlapping sheets of plywood and a couple of guys would replace the rollers as the beam moved ahead.
Had no problem whatsoever holding the beam in check at all times.
The rope was 3/4 poly, the run about 300ft with about a 20 ft drop.
The rope brake worked like a charm and we were able to position the H-beam within inches of its resting place.
Helpers would, as the beam moved foreward, simply use levers (crow bars) to steer the beam into position as required.
Stopped you could not move it, but in motion you could lever it any which way.

While a crane would have been the correct method, the monster crane we would have needed (1000 lbs @ 300ft) would never have been even able to get one on site.

Be careful!

 

[BruceWard]

Good suggestions but I should have explained more. I have a fixed galvanized cable and want to use this brake as an emergency (or parking) brake. I need something to clamp on the fixed cable.

I have thought of using three rods, two running under the cable with a third above the cable between the two below. Normally these rods would not touch the cable but if the top rod was pulled down it would cause the cable to be clamped between the three rods.

Something like
.
---------------
. .

Which would become

---------.'.----------


I have also thought about using a wire rope clip with springs to keep them spread (the loop pushed up) until pulled from below.

I believe there may be commercial systems that use brake pad like material.

I would like to find a long lasting, reliable solution that will cause minimal harm to the cable.

 

[DieselPower]

What kind of parking brake? I'm curious because the cable is so big. If it was a regular parking brake application like found on equipment or vehicles I would simply suggest a lever lock style park brake handle like medium duty trucks use to use in hydraulic brake applications. Shoot, I even have a Kamatsu park brake lever and a couple of cables you could have for free if you thought they would work. How much travel will the cable have or does it need to move freely over it's entire length?

Something else to consider might be a modified trailer tie down strap load binder. The kind found on tractor trailer flat bed trailers that use 4 inch tie down straps. You could modify it to accept cable and use it kind of like a manual winch. The replacement ratchet assemblies are not very expensive.

 

[BruceWard]

I am not doing a good job of explaining.

I am building a large scale zip line like car riding from five 5/16" cables. It will have significant steel and concrete structures at the top and bottom. There is approximately 170' of horizontal and 90' of vertical between the top and bottom piers. The car will be raised and lowered by multiple hoists driving two large spools with two additional 5/16" cables.

The top cables that the car will hang from have a combined break strength of almost 50,000 pounds. The two cables raising and lowering the car have a combined break strength of 20,000 pounds. The car and its contents should never exceed 2,000 pounds. So there are significant safety margins.

I want to have one or more brake systems in case the pull cables were to break or any other failure were to send the cart racing for the bottom. I would like to place a "cable brake" on each of the 5 5/16" cables that the cart hangs from.

 

[DieselPower]

Ok, now were getting somewhere. Big cables for a big load. Are you using electric winch's or a mechanical device to extend and retract the cables? I would suggest incorporating some kind of broken cable detection system no matter what the configuration. Is this system already in the works or still in the planning stages. The reason I ask is it will be much easier to buy a hoist system that has a built in safety brake then incorporate one into a existing system. Electolift should be able to supply hoist with integrated brakes and broken cable detection systems. Electric Hoists Wire Rope Hoists by Electrolift J. Herbert Corp. is another company you might try contacting for braking systems. J. Herbert Crane Corporation - Cranes, Hoists, Parts, Services, Testing and Refurbishments

 

[SimS]

How about something like these?
come along clamps, stringing blocks, wire stretchers, pulley blocks, climbing irons, cable stripper, ropes for pulleys

Good luck;

SimS

 

[PILOON]

OK, with the additional info;

Maybe you could fab something along these lines (you must weld and be quite handy from details so far)

How about a car rear brake shoe that is manually levered to clamp down on the cable, probably located between your 'cable car' pullies (assuming 2 wheels per cable). One brake shoe per cable, I guess would be in order.
Would have to be manual unless you have electricity on the 'car', in which case you'd then be talking big electro magnets to pull the 'brakes' on.

LOL, calculated length of bungee cord designed to 'slow the cab just in time' before reaching the bottom!

 

[Pooh_Bear]

Get in touch with the ACME company
and order a big spring to go on the bottom pier.
The cart will eventually bounce to a stop.

E ticket ride for sure.

Pooh Bear

 

[BruceWard]

Thanks for the links and suggestions.

I have asked for quotes from several hoist and winch vendors. So far the standard products are either too short on cable or too slow. The custom quotes have had an extra 0 or two added to the end. I like the idea of using multiple hoists or winches to drive the car removing any single point of failure. My intention is to use a 2 + horsepower shop hoist, remove the spool and use sprockets and chains to drive a larger spool with 180' of cable. If needed I will chain two shop hoists to each spool. I plan to build two of these drive units. Shop hoists are convenient that they already have the brakes to hold the stopped load built in. They are faster than winches and designed to run on AC.

Come Along Clamps may be the solution I need for braking. I have been looking at "Wire Rope Grabs" as well. I plan to order some of these and test them.

I also like the idea of using an automotive brake pad to pull down on the cable.

I intend to have the cable attachments at the uphill side of the car spring loaded so that if tension slacks (cable break) the brakes will automatically trigger. I also am considering a speed based trigger. I believe the output from a small motor and pulley, acting as a generator, running along the pulley could be used as an additional brake trigger.

 

[kthompson]

Bruceward,

Another suggestion, IF this will be insured, ask them what type of brakes they require if there is specs on what it must have. They may have specs or they may give you a blank stare.

 

[BruceWard]

Do you have any suggestions on where to obtain insurance for a residential cable car or tram?

 

[Pooh_Bear]

An idea just occurred to me.
Make the cable pass around a cable drum on the cart as the cart moves.
Add brakes to it like a car or truck. Can be mechanical or hydraulic.
The cable drum would spin free except for when the brakes are applied.
If the cable has enough friction on the drum the cart should stop when the brakes are applied.

If you can't get a giant spring from the ACME company then at least
put a pile of old tires at the bottom to cushion the landing.

Pooh Bear

 

[DieselPower]

Hmm, now that's a good idea Pooh Bear. If regular automotive brakes wouldn't provide adequate braking power and have a air source you could use a truck air brake system. You could pick up one or more used air brake backing plates off truck axles fairly cheap with the drums, shoes, slack adjusters and brake chambers. A 16.5 inch diameter drum, 6 or 8 inch shoe would provide massive clamping force. Plumbing the air system would be rather simple.

 

[MikeD74T]

Pooh Bear has the right idea. Put disk brakes on each end of the spool. MikeD74T

 

[MarkV]

What do they use on elevators? I know they have a automatic braking system to stop a free fall.

MarkV

 

[tommu56]

are you trying to go up hill or across a creek

the small cable cars I have seen have a right angle gear box on car and awire that runs to power to run motor and the tugger cable goes around the capspin about 4 or 5 times and there are 2 other load bearing cables and car is hun below them.

tom

 

[BruceWard]

It is going up and down a hill. The distance is in the 160' to 180' range depending on where the top landing is placed. The slope is close to 30 degrees. I intend to have the drive system at the top.

I have revised the plans to build to cars and two tracks. The plan is to have two puller cables. Each puller cable connects to both cars. Each puller cables wraps several times around the spool on two hoists. The hoists are placed at the top of that track and act both as a drive system and as the pulley to make a 90 degree bend in the pull cable. The pull cable will be in a U shape with a hoist at the bottom of each leg.

 

[Philscbx]

I have revised the plans to build to cars and two tracks.

Just to be clear, there will be 2 cars, and sounds as if they are each independent.

One can travel up while the other stays behind.

I think the term 'track' is throwing a curve.
Is there a actual track in the design?

* And 2 cables, pulling both cars.
Each puller cable connects to both cars / this one has me stumped a little.
Is this a backup feature if one hoist is out of service?

I'm not sure if both cars ride the same direction at the same time and next to each other, (one in front of the other), or independent of each other.
With either hoist towing at will one or both cars or both hoists at the same time. Could have a speed issue difference.

With the existing 5 support cables, it passes through cable bearing trucks
(a beam with 5 pulleys at each end) or hanging with only 5 pulleys, it could crab and or try to walk across cables.
Unless other stabilized guide system is devised.

Possible storm damage.

If I recall, the tram system support cables are counter balanced for the load.
If the load ever exceeded the load cables, the cars would get closer to the ground.

The 5 cables carries the weight of both cars, and is your brake control. Brake control within the center of beam.
Brake control could be 2 large flat plates lined, 5 grooves.
Bottom plate ridged, top plate floating above cables from springs between the plates.

The beam with wheels at each end keep the cables running true and flat through the brake plates.
Simple lever inside car roof applies floating plate in clamp mode.
Never touching cables otherwise.
Small trailer leaf spring is the clamping force that lever pulls down on.

Brake on mode would have to lock out either traveling hoist from starting.
A rope could extend out of car to apply brake. Or release.

Now the tricky part, lowering the car with it's hoist.
How much of the car is left with the truck on the cables.
I think I'll leave that one for now.
May have to create a docking hub.

Regardless, it will be fun however you do it.

**
Otherwise alternate design, one is on the way up and the other is on the way down.
Not possible with this one I guess.

Like the tram in Palm Springs Ca. that I have ridden several times.
A wonderful setup. Palm Springs Aerial Tramway Home
Semi counter balanced load.
And clearance to pass each other in high winds at high speed.
The cars even rotate 360 degrees while under way.
Don't pass this up if going through.