Originally Posted by vishnu gautam

Sir,

i m doing a power calculation for a sufficiently long (19 m) traveling tripper. Does the material on its inclined length introduce any horizontal resistance for the motion rather than to add up the wheel load? the tripper having almost 12deg inclination. the material conveyed is coal.

also to check the slippage during starting and normal running what procedure to follow and what reference be taken for various friction factors?

thanks & regards,

Vishnu

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Greetings and salutations Vishnu,

The (www.cema.org) web site can help you with everything as well as our many knowledeable members

The up and over pulley to the chutes is carrying all the weight of the belt and coal the minute it leaves the troughing idlers and the empty belt is pulled down through and under the lower pulley under tension.

Not knowing the belts carrying capacity, surge pile belt length, the belt width, the troughing angle of the idlers, the idler spacings, whether the up and under pullies are lagged is what should be explained by you.

I am unsure the short amount of loaded belt is a serious issue and if it is really a factor as the drive unit gear box and motor of the system is where all the work is done pulling the entire length of loaded and empty belt depending on the position of the tripper whether fully extended with a full belt or retracted with almost no load.

The actual weight of that section of conveyor belt and its weight of coal per foot is the issue.

The stationary conveyor drive for the tripper belt delivery system is what runs the business end of the tripper-at least ours did.

The weight of the coal and the conveyor belt and rolling resistance of the troughing and return idlers, the dump over pulley feeding the chutes and the under pulley returning the belt are what delivers the additional resistance to the system.

I am assuming you have a two pulley tripper with a winch drive to tow it back and forth across the surge pile and the tripper is mounted on steel wheels that ride on a v rails to carry it. ■

Searching brought up the following threads --

https://forum.bulk-online.com/showth...=tripper+power

https://forum.bulk-online.com/showth...=tripper+power ■

External forces are the rolling resistance, belt tension differential & wind resistance. When the sum of those is factored by the travel speed you will obtain the power consumption.

Wheel to rail friction is steel to steel with water lubrication if it ever works in the rain. Weight transfer at start up can result in wheel spin: unless it is a towed tripper of course. To reduce/eliminate wheel spin you must drive as many wheels as you can if your C of G is high enough to justify the consideration. It depends on your wheel loads. ■

Originally Posted by vishnu gautam

sir,

as you mention in point1) Not to consider the material weight. Does the rolling back of material on the inclined surface of tripper will make any difference?

If you have bulk rolling back on the belt,1. the belt is either to steep in the approach(The tripper over pulley is too high in relation to the tripper frame or the belt is overloaded). 2 the conveyor is overloaded or the bulk is too large in its broken form.

The tripper belt speed must be the same speed as the delivery belt. (ours was).

If you are moving 2200 ton per hour of broken bituminous or sub-bituminous coal with the 12 degree incline you will not want a motorized tripper.

A typical tripper will have a taunt wire rope messenger cable trolley strung along the belt to carry the control wiring using insulated wire harnesses/turnbuckles that slide along the wire rope following the tripper as it travels from end to end of the support frame

In mines using a surge pile they anchor the wire rope cable to the mine roof with angle iron and roof bolts to hold it in place under high tension allowing free travel of the power cable from end to end with the tripper in both directions

A rail mounted tripper with grooved wheels will use one common electric double drum winch for simplicities sake attached to the opposite end of the tripper belt.

The only control on the operators platform is for the forward and reverse operation of the winch travel.

A tripper belt drive is typically at the head end of the surge pile where the gravity belt take up is located to make things simpler to maintain. and allow a clear path for the tripper.

The wire rope for the double drum winch will be threaded under on one small drum and over on the other to facilitate opposite movement just as is done with a double drum mine winder.

Normally having two sheave pulleys at both ends of the tripper frame to carry the taunt winch rope from the far side of the sled to the outer drum of the winch is sufficient cable to move a tripper with the other winch cable inline with the tripper maintaining a constant tension on the sled acting as retarder to maintain a single rate of speed the winches revolutions per minute

allowing easy movement in both directions as the winch is pulling the wheeled sled of the tripper in one direction at a time providing a linear tug/tension in the center line of the tripper sled.

The double drum winch acting on the multiple pulleys exerts more usable mechanical advantage/ linear pulling force/power to pull the tripper sled simply due to the four fold mechanical advantage of the cables and 4 pulleys/sheave blocks.

A tripper will always get a lot of dust affecting its tractive effort so take that into consideration as you would not want driven wheels on the rails for the tripper itself in my opinion.

The double drum winch is the easy way to solve you problem and reduce wiring headaches as you will be constantly going back and forth with a heavier trailing cable.

Also using an exposed three three phase buss contactor system is bad idea simply due to coal dust and its ability to cause explosions and fires. ■

Originally Posted by vishnu gautam

........

Also its2200tph conv and tripper is having 6 wheels, i m presently assuming 2 motors on each side middle wheels. The wheels are on a horizontal rail track.

For 6 wheels you need a pin jointed frame set up; other wise the drive will lose traction altogether when the outer wheels are on higher ground. Check your allowable track tolerances/settlements & you'll get the picture. ■

Originally Posted by vishnu gautam

mine is the conditional requirement of using the motorised tripper. Also the tripper moving weight is too high(approx 35T). Also the Tripper Travel is much long.

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Vishnu is this for a desired design from a client or a engineering class project?

As a long as the wire rope tension is taunt there is no problem in towing a tripper of this size or weight with wire rope and a double drum winch, it is a not issue.

As long as the the double drum winch has enough drum capacity to allow full travel from one end to the other with out layering the wire rope it will be more efficient to use and cost less to build.

Unless you are constantly blowing the dust off the rails you will always have problems and the driven wheels on a tripper require more work and a heavier carriage-do not forget the driven wheels are also pushing against the no driven ones that may have a lot of coal dust in front of them; the wire rope winch will pull the carriage regardless of the dust unless it is so deep it simply cannot move.

You could simply have an X number of passive wheel sets under the carriage and use a wire rope winch with four pulleys/sheaves, two in the middle for the linear pulling and two on the outside of the carriage track to pass the wire rope on the outboard side.

Using a wire rope winch is a lot less work and less complicated to wire and operate.

For all the work you are doing a large plow conveyor may be an entirely better answer for the entire system as it will be not have any problems carrying coal. ■

Vishnu,

You clearly know what you are doing. I agree with your methods & would like to encourage you in their fulfilment. With a pin joint you can easily absorb the track irregularities within the reasonably accepted irregularities of a belt line. With your astute design acumen a modicum of reserve is understandable & appreciated. But don't translate worthy concern into worry.■

Originally Posted by vishnu gautam

I appreciate your response.

Yes, its a Client's requirement of using the motorized tripper.

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I guess if it were me I would rather lose a sale/contracting bid than a customer.

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The steel support structure will be much larger and heavier than necessary.

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The entire horizontal structure of our surge pile tripper was supported by the mine roof and anchored at the end piers which also supported the weight of the drive unit and gravity take up.

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You have to do more design work to be able install and remove an additional motor and gear box when failure occurs.

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The plow conveyor or non motorized tripper has fewer parts.

plow conveyors and non motorized trippers have been in use for many years.

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The catwalk in conjunction with a plow conveyor rides over a a series of open chutes/skeleton framing with a U turn at the end to to push and carry coal is less work.

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How fast can the coal be taken away and loaded to its end use?

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What harm is there in keeping it simple? granted the scenario of "I designed it and I do not have to fix it" comes to mind buuuuuuuuuuuuuut.

Refer back to the first paragraph.

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A road map does not equal experience.

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My opinion only ■

Originally Posted by vishnu gautam

Sir,

i m doing a power calculation for a sufficiently long (19 m) travelling tripper. Does the material on its inclined length introduce any horizontal resistance for the motion rather than to add up the wheel load? the tripper having almost 12deg inclination. the material conveyed is coal.

also to check the slippage during starting and normal running what procedure to follow and what reference be taken for various friction factors?

thanks & regards,

Vishnu

Dear Mr.Vishnu,

I am from maintenance, not from design department. I have seen our stacker moved without command, when it was handling very high TPH of iron ore pellet. I feel that the material load on the inclined portion of the tripper certainly has the effect on the tripper drive and it's wheel.

Regards, ■

Originally Posted by sganesh

Dear Mr.Vishnu,

I am from maintenance, not from design department. I have seen our stacker moved without command, when it was handling very high TPH of iron ore pellet. I feel that the material load on the inclined portion of the tripper certainly has the effect on the tripper drive and it's wheel.

Regards,

That is something I totally forgot about sganesh, the weight and mass of the ore will have an effect of pushing against the tripper head pulley.

The winch cables will hold it in place too eliminating that from happening. ■

"Force is that which changes, or tends to change, the state of rest or uniform rectilinear motion of a body." Sir Isaac Newton:: Philosophiæ Naturalis Principia Mathematica, first published on July 5, 1687

Various components of material weight and inertia result in changes in belt tension throughout the tripper. Accordingly the tension difference between the inbye & outbye includes the conveyance contribution of the material to the resistances to motion.

Now::

There is a laden weight to be considered when evaluating the rolling resistance & that will include the burden weight.

Material can smack a headchute, or not, producing an impact which contributes to the motive force demand. Or does it?

Sometimes material slides off to one side only and this can push wheel flanges into a rail bulb which then modifies the rolling resistance.

Falling material impact can also increase the download on the wheels & that also will affect the rolling resistance.

There's more to cardboard boxes than meets the eye.

PS. I am a rope aficionado; but in this application I fear that the safety issues with a long exposed rope length mitigate against the simplicity.

My father used to tell me about disembowelments, decapitations & amputations due to rope breakages down in the mine. He suffered a severe eye injury from a snapped rope; but sight was preserved by a diligent doctor & he continued to work with ropes. ■

When attempting to analyse the loads on a anything I usually find it helps to construct a free body diagramme.

http://www.wisc-online.com/objects/i...p?objID=TP1502 ■

Vishnu,

Material is sustained on the belt by the tension. That's all there is to it: if you cut the belt there will be no material on the tripper. For a stationary belt the material moves at the same speed as the tripper. Simply multiply the tension difference by the tripper speed to reach the power requirement. Continuum considerations can be as follows: If you move towards the fixed conveyor drive then you can add the tripper speed to the belt speed when factoring the tension difference by the speed: and vice versa.

Then there's just impact on the headchute to be considered & you've cracked it.

Tractive effort is the sum of rolling resistance, wind resistance, gradient resistance plus the tension differential. Rolling resistance is the total download factored by the coefficient of rolling resistance. ■