Correct sizing for a belt driven pump

[wessels147]

Hi,

I need to replace the engine of a waterpump. The new 50 HP diesel engine can only be mounted on top of the pump. The easiest way to drive the pump would be with two pullies and a belt. The pullies should have the same diameter. The available space is between 3.5" and 5" in diameter for the pullies

Now the questions:
One or two v-belts?
What size of belt, eg type A, B, C etc
What diameter should I choose, smaller or larger?

Is there a online reference for these problems?
Are there any rules of thumb?

Could you also motivate your choice so I learn something from it.

Thanks,

Frederik

 

[Philrock]

What rpm? What center distance?

 

[wessels147]

2900 rpm is the operating speed of the pump.
But sometimes I run it on a lower speed, till 2000 rpm.

The center distance between the two shaft will be between the 15" and 25", but the lesser the better.

 

[ccw]

Hi Wessels147,
For what it is worth, have you seen the "Orange County Chopper" show on TV? Some of their custom chopper bikes have a large toothed flat belt (timing belt) running from the V-twin engine crankshaft back to the clutch and transmission. The power/speed/dimension range you are going to use looks about right for what they are using. There are at least three advantages there:
1. the toothed flat belt and sprockets develop operating torque without having to put otherwise alot of pretension on the setup as you would with a multi-vee belt.
2. if you can keep the shafts parallel within a few thousandths and assemble the system, a single wide flat belt will stay in tension across the width of the belt better than a multi-vee belt arrangement (hard to keep all those vee belts pulling equal).
3. the thin, toothed, flat belt / timing sprocket set up is more efficient that the vee's, so you will burn less fuel for the same work.

 

[wessels147]

Thank you ccw, for the suggestion and motivation.

Timing belts are hardely used in agricultural machines, so it may difficult to obtain the pullies. Can you give me a suggestion what kind of belt I should use? The pump shaft is 1".

Still I would like to know what kind of a v-belt setup I would need for this project (as a plan B).

Thanks,

Frederik

 

[haggis]

There is an excelent document on belt drive design at:

http://www.cptbelts.com/pdf/catalogs/vbelt_all.pdf

 

[Philrock]

Browning Gripnotch belts that might be appropriate are:

"B" section, rated 10.48 h.p. per belt at 2900 rpm on a 4.8" p.d. pulley. 6 belts would get you a 63 h.p. rating. This would give you only a marginal service factor. My Browning catalog does not list pulleys with more than 6 grooves at the diameter you require. Rating at 2000 rpm is 79% as high.

"5V" section, rated 15.54 h.p. per belt at 2900 rpm on a 4.8" p.d. pulley. 5 belts would get you a 78 h.p. rating. This would give you a much better service factor. Better still, use 6 belts. Rating at 2000 rpm is 75.5% as high.

Note that the Browning Gripnotch belt has raw rubber edges which are good at transmitting power. Fully encased belts will stand up to the elements better, but have lower power ratings.

 

[sreid]

Take a look at Gates.

http://www.gates.com/index.cfm?location_id=560

 

[ccw]

Hi again wessels147,
As you can see the Vee Belt approach is getting cumbersome. If you are still considering the flat belt current century stuff try this catalog:

http://www.dodge-pt.com/literature/catalogs/pt_components_catalog.html

The catalog specifies both the belts and matching sprockets. Based Rockwell/Dodge's data it appears that a single 3.35 inch wide belt, 8mm tooth pitch and two taper-loc mount sprockets at 3.81 Pitch Diameter would transmit your 50 HP at 2000 RPM.

As another point of reference, if you check out the later model Bobcats, the hydraulic PTO is run by a approx. a 1.5 inch wide flat belt of the same type. My friend says dead heading the hydraulics will pull his 72 HP Bobcat engine down, which speaks well for the torque capability of the flat belt.