Belt Slippage

we have adjusted the belts with proper tension. i make a mistake, it has 6 belts not 5. here is the pict

Yet another good answer.

Here is a online Pulley And Belt Calculator calculator that may help you.

It does not give horsepower so it can not give the required number of belts, but it does give you the required Minimum Belt Wrap Angle

looking at his pic I highly doubt this is a "matched set" situation. but it is a point to consider.

That use to be a concern years ago, not so much anymore. Most manufactures keep the belts pretty closely matched in size.

Unless they don't get replaced as a 'set'.

My 1st thought is to get a look at the surface of the drive pulley, we cant see if its become shiny and polished, I'd start there and fresh belts.

From the appearance of the visible part of the guard, it appears the current motor pulley may be smaller than the original pulley. (Perhaps this was done to change the pump capabilities?) If so, this reduced the torque (power) capacity of the drive. In any case you need to calculate the drive's power capacity and compare it to the motor's horsepower and the pump's requirement. There are sources available on-line. Since this is a reciprocating pump, make sure you use the correct service factor. Also, make sure you use the correct v-belt system.

By the way, compare the 2 drives:

* Center distance

* V-belt part number

* Drive pulley diameter & grooves (or part number)

* Driven pulley diameter & grooves (or part number)

* Motor horsepower and RPM

* Pump stroke and plunger size

Actually, decreasing the drive pulley diameter increases available motor drive torque, decreases pump shaft speed, and decreases belt-to-pulley surface area friction.

Triplex pump is a piston pump. You have said this pump is use for back up so it's not ran on a regular bases. How long does it sit before use. What PM is being done on the pump. Could have a sticking valve that loads the motor and cause the belt to slip. A sticking intake valve would load the motor and reduce the pressure. There could also be problems in the transfer case that's driving the pistons. Some one else brought up the observation that the driven pulley looks a little large for the guard enclosure. Has it been changed? Check it to the other pump. Not knowing what your pumping there could be problem on the cylinder walls that is cause by the fluid just sitting in there. Is the pump being drained after use. Though you have a slipping belt it may just be a symptom of another problem.

Have you checked the belts tensions ? did you compare them ? Your pic does not show if you can regulate the tension.

No slip you want?

Dear Mr.iphun,

You have not mentioned the Speed Reduction Ratio, and Distance between the Pulleys, and the Quality of the Rubber used for the Belt, and its Elasticity, which decides the, stretching Character of the Belt, and the Efficiency of the Power Transmission.

If the Reduction Ratio is is more than 4, chances for Slippage are very high. If the Distance between pulleys is smaller than required again the chances for Slippage is higher.

The angle of wrap should not be less than 120 Degrees in the smaller pulley, which decides the distance between the Pulleys. Idler should be used to improve the wrap angle.

You have referred that you are using 6 Nos. of V Belts. Pl. ensure, you are using the V BELTS manufactured in the SAME BATCH and please DO NOT MIX BATCHES for the same dimensions of the V Belts.

DHAYANANDHAN.S

But that, and other posts, does not explain why one of the pumps is OK but the other has belt slippage (which I believe he says in original post, though not entirely clear)

Did you try poly-vee belt drive?.

One possible solution is to fabricate a roller pushing the belt to stretch or tighten tension. In this way you will increase contact surfaces of belt and pulleys on their periphery.. You can not do anymore with the size of the driver pulley and the pump's. It must have been intended to maintain rpm ratio of drive to driven shaft.

yeah mr. codemaster is right

i dont know either why this pump get this problem. but the other is not. the other is same pump. same design. but there is not problem like slippage belt like this. so, this pump rarely run. this pump just run if there is a problem in the another pump, like repacking and replace the plungers. was this pump could run 8 hours, in 145 kg/cm2 then the belt slip. but now in a minute when reaching 125 kg/cm2 the belt is slip

we use OEM belt, 3vx-710. and ratio 4.66 :1

"Require 5 v-belts with tooth design" - "So my boss machining the surface of groove of pump pulley because the surface is corrosive". Can you explain more clearly what you mean in these two phrases?

I mean it is COG type.

So has your boss machined off the teeth?

From the photo it looks more like a raw edge cog belt than a toothed belt. The difference being that the visible "teeth" are really only to provide higher flexibility than would be available in a higher profile belt, there is unlikely to be mating teeth on the pulleys.

My first reaction would be to apply a liberal dose of CRC Belt Grip or similar and then recheck the temperature as it may simply be slip friction that is generating the excess heat.

Taking everything else into consideration have you measured the electrical load on the motor for excess current draw and examined the pump for proper speed, bearings and impeller for misalignment, excess wear, lubrication failure, etc.

I suspect that the pump is running "tight" and the extra mechanical drag is causing the belts to slip. Adding an idler pulley will probably make the problem worst by introducing additional lateral/radial forces on an already misaligned shaft/bearing combination; you'll know soon enough if the belts start failing even quicker than before.

Also, if the belts have been over-tightened to eliminate the slippage, the motor bearings themselves may have been damaged.

Come to think of it, how does OP know the belts are slipping?

I'm convinced the problem is exactly that "machining" done on pulley. ALL grooves MUST be in close tolerances for the system to work, and groove angles must ALL be spot on to specs. Machining-off the rust is by far NOT enough. S.M.

That (i.e. what machining?) is what I was trying to drag out of the OP in #13.

If a toothed belt slips, there's something very wrong.

Don't think we're dealing with toothed belts, just parallel V-belts. The "teeth" visible in the inner belt side, just make the belt more flexible. But I totally agree on the machining being the root cause, as the depth each belt sits, i.e. the equivalent diameter it works at, must be identical for all after machining, plus run-out must be minimal, and that's not all that easy to achieve. S.M.

Check belt tension

Contact the designer and ask for instructions to check alignment & belt tensioning methods or check websites.

V belts pull with the SIDES of the belts.

The photo looks like the belts are riding very deep into the groove,indicating a worn pulley.

No exactly clear from photo,but looks like it to me.

If your boss has altered the groove angle or depth, with his machine work, that is your problem.

Check the dimensions of the pulley groove specifications vs the belt number.

Machining is the issue...are you sure the belts aint bottoming out??...then you have slippage..

If I read your post correctly,you determine that you have slip because of the temperature of the motor and pulley is higher than normal.

Use an adjustable strobe light to determine if and how much slip you have,and on which pulley the slip is occurring.

Put a chalk mark on both pulleys,and on the belts,at the same position, while they are stopped.

A chalk mark across all of the belts will also be beneficial for information as to which particular belt or group of belts is slipping.

Start the pump,and synchronize the strobe light to freeze motion on the marks on the belts.

If you see the marks drifting,you have found your slip.

They will slip initially during start up,but should remain stable when running.

If you have no slippage,check motor amps and voltage under load, compared to name plate data,factoring in the S.F. (service factor) of the motor.

The belts could be too tight, (yes,too tight will cause excessive heat also by adding

extra load on bearings and motor) or you could have a bearing issue in the pump or motor.

Excessive load on bearings is very destructive to the bearing life.

If a bearing is running at twice the rated load,the life of the bearing is decreased by 90%.

If a bearing is running at twice the rated speed,the life is decreased only 10%.

I think that the initial slippage may have been corrected,but the new belts may have

been over tightened.

New belts will run a little hotter when new,but after a few hours of run time,should settle down to normal temperature.

Good luck.

Thank you everyone. After running for a minute i look in the belts. They have a little contact in the pulley. I replace all the belts. Set in little tight. And add some belt dressing. It is ok. There is no slippage anynore. It have been 2 days. We always check for vibration and temperature. Anyway. This pump capacity design is 2.37ton /hours. But when this running until 2.50 ton/hours. Speed motor design is 1465rpm. But when i measure is 1500rpm Could it possible just excessive 35rpm add some capacity ?

Thanks everyone I set the belts in proper tension. And add some belt dressing. It have been 2 days that pump is running. There is no slippage anymore. But there is one more thing i want to asking. This capacity pump design is 2.37 ton/hours. But now is 2.50ton/hour. And not decrease Speed motor design is 1465rpm. But in actual is 1500rpm. Could it possible excessive capacity from excessive of motor speed ?

You motor is running at synchronous speed,(presuming 50 hz), which indicates it is

very lightly loaded.

The 1465 speed is the design rpm under full load.

Yes,the increase in speed will increase flow of the pump.

An increase in flow should result in an increase in load,so there are obviously some

other factors that we do not know about your application.