Pump and pully ratios

[tman7]

I've got a Cat pump 290 that's driven by a 3 inch pulley on a #4 blower which runs no more than 3000 rpms . The specs say the cat is capable of 1200 psi but the max I can get out of it s 525. So obviously my pump pulley is limiting it. Can anyone explain how the math works for determining pulley size vs Psi on one of these? I would like to have 800 Psi available.

Thanks

 

[scotty747]

i was wondering the same thing. i was thinking i would have to switch to a bigger pump

 

[Bob Savage]

The Cat 290 is capable of 1200 PSI @ 3.5 GPM.

I've got mine turning at about 1300 RPM to supply 2 wands. It's been purring away for several years now with very little maintenance.

You need to increase the pulley size on your motor going to the Cat, or decrease the pulley size of the pump, in order to spin the pump faster. If you're only getting 800 PSI, you may need a different unloader or back pressure relief valve on your machine.

If it's a clutch on the pump, it's easier to bump up the motor pump pulley and change the belt to a smaller size.

 

[RichardnTn]

Unscrew your regulator, take the spring out and put 2 small washers behind it and put the spring back in.... most regulators have optional springs to vary the pressure.....this will do the same thing....

What are the pulley sizes on the both the pump and blower.... 3" on blower ?
Richard R

 

[bob vawter]

switch to a Para Plate By-pass Regulator...it's a CNC billet stainless steel unit that will last till your kids get old....and will easily be capable of more than yor pump can produce

 

[Shane T]

Make sure the rest of your plumbing is rated for those higher pressures.

 

[TimP]

If it's an older Hydramaster CDS it may be reduced because the heat exchangers may not can handle it. I know with mine they advertise 1200 and you can only crank it to 850 stock. You have to put in a stiffer spring to open the pressure valve more to get the pressure or put something in there to create more pressure on the spring.

 

[Duane Oxley]

Here's a question...

How long have you had the machine?

If it's new to you, then you aren't likely to know from experience what it's capable of, so if it's doing less than you expect, you could have a mechanical problem with the pump itself, or the regulator, or the jet size, or a combination of factors.

If you've had it for a while, then it could very well be as simple as a worn out O-ring in the regulator, etc.

To get the pulley ratio, you need to know the size of both pulleys... not just the one. A Cat pulley, for instance, typically is larger than a clutch, but not always. Assuming that you have a clutch, you are "okay", ratio- wise, because the pulley size you state is actually a bit large, but compensated for by a slower turning motor, so it should balance out.

In truth, a Cat 290 with clutch, driven by a 2.5" pulley, is still turning faster than Cat recommends... and, with that kind of ratio, at 3.200 RPM on the motor, the pump will deliver 1,400 PSI @ 3.5 GPM, which is just enough to warp the head, if the head is the standard bronze one...

So, my guess is that you either:

1.) have a regulator "situation"

or

2.) have a cup problem (i.e., a ripped , torn, burned cup or cups, which compromise the ability to deliver flow rate, which in turn compromises the ability to generate pressure...

Does it have the pressure you want, until you pull the trigger?

What kind of regulator? As Richard said, it could also be the regulator spring. And some regulators can be "helped", by adding a washer or two between the spring and the adjustment knob...

 

[tman7]

Here's a question...

How long have you had the machine?

If it's new to you, then you aren't likely to know from experience what it's capable of, so if it's doing less than you expect, you could have a mechanical problem with the pump itself, or the regulator, or the jet size, or a combination of factors.

If you've had it for a while, then it could very well be as simple as a worn out O-ring in the regulator, etc.

To get the pulley ratio, you need to know the size of both pulleys... not just the one. A Cat pulley, for instance, typically is larger than a clutch, but not always. Assuming that you have a clutch, you are "okay", ratio- wise, because the pulley size you state is actually a bit large, but compensated for by a slower turning motor, so it should balance out.

In truth, a Cat 290 with clutch, driven by a 2.5" pulley, is still turning faster than Cat recommends... and, with that kind of ratio, at 3.200 RPM on the motor, the pump will deliver 1,400 PSI @ 3.5 GPM, which is just enough to warp the head, if the head is the standard bronze one...

So, my guess is that you either:

1.) have a regulator "situation"

or

2.) have a cup problem (i.e., a ripped , torn, burned cup or cups, which compromise the ability to deliver flow rate, which in turn compromises the ability to generate pressure...

Does it have the pressure you want, until you pull the trigger?

What kind of regulator? As Richard said, it could also be the regulator spring. And some regulators can be "helped", by adding a washer or two between the spring and the adjustment knob...

I talked with someone at Jon Don today and he suggested the same thing; the problem is either the regulator or pump he doesn't recommend changing the pulley ratio as the Hx is only rated for 800 Psi anyway.

Ive had the Cds for a little over a year and never ran it over 400 Psi until I got my Greenhorn Wand. It is an older machine, and the regulator is probably the original so Ill fart with that first, then pull the pump apart and see how the the parts look.

Thanks for the replies.

 

[glenboy]

i would go with the paraplate ss regulator that bob talked about forget washers and all that garbage