Direct Drive question

Chris Tharpe said:
I have had a few DD pumps for the last couple years, the only problems I ever encounter is with the cheap engines, the pumps are never a problem

Also Tony, look into the RKV 55g40 AR pump, its 5.5 at 4,000 but on a 13hp it will do 2500ish
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Thats the same setup I have, works great! Got it from Russ Johnson

I used to have the pump/engine a foot higher then the tank outlet and it still worked fine. That paticular skid tore up so I mounted the machine to a wooden skid on the floor and now the fittings are pretty level with each other.

You guys can do all the math you want but I dont see why each individual unit wouldnt pull enough water to flow itself. With both machines combined he could then get the added volume hes looking for.
William has a point with the law of hydraulics part of the equation. Tony might not get 9gpms but he shoulnt be to far off from it.

My 2cents
 
PressureWashE said:
Example
(1.2192 = 4 feet in meters)
P = pgh = 1 x 9.8 x 1.2192 = 11.94 kPa = 1.73 psi

1 psi = 6.9 kPa

p = density of the fluid (kg/m<SUP>3</SUP>)
g = the acceleration due to gravity = 9.8 (m/s<SUP>2</SUP>)
h = height of the fluid (m)

Halliburton days paid off, lol I had to pull out my cementers book, to find the formula, so what that being said, it looks like to keep up with 9gpm, you would need more psi, or an electric pump, to send water to your units
Click to expand...

Either your math is way, way, way off or you just don't know what you are talking about.

I can feed 3 machines at the same time from my 325 gallon tank. The Hotsy is a 5.6gpm and the pump inlet is about 2' higher than the outlet of the tank. The Landa is 5gpm and about 1' higher than the outlet of the tank. The Pressure Pro is 8gpm and about 1' higher than the outlet of the tank.

As long as you have enough supply feeding the tanks you will not run out. I can have all 3 machines running and no problem at all, all coming out of a 2" bulkhead opening with 2" "T"'s supplying the machines.

At one time 2 years ago I had the 8gpm Pressure Pro, the 5.6gpm Hotsy and the 6gpm Bandit roller pump pulling from the tank at the same time.
 
Chris with all due respect, Tony is enquiring about using 2 direct drive units, that would total 9 gpm plumbed so he can use, 1 gun at 9 or 2 at 4.5 each, every unit you just mentioned is either belt driven, or gear drive
, the lower rpm on the pump allows you to suck water, wear as the direct while it will suck, will require more of a constant pressurized feed,

I also use a 325 tank with 2 landa 5.5 plumbed to it with no problems, but they are both belt driven, I wasn't saying this isn't possible, I was simply posting the math of the hydrostatic peressure, and just going on what I've heard about direct driven units, I however have never used a direct driven pw from a tank so I don't know first hand if it will work or not
 
PressureWashE said:
Chris with all due respect, Tony is enquiring about using 2 direct drive units, that would total 9 gpm plumbed so he can use, 1 gun at 9 or 2 at 4.5 each, every unit you just mentioned is either belt driven, or gear drive
, the lower rpm on the pump allows you to suck water, wear as the direct while it will suck, will require more of a constant pressurized feed,

I also use a 325 tank with 2 landa 5.5 plumbed to it with no problems, but they are both belt driven, I wasn't saying this isn't possible, I was simply posting the math of the hydrostatic peressure, and just going on what I've heard about direct driven units, I however have never used a direct driven pw from a tank so I don't know first hand if it will work or not
Click to expand...

It helps when you read the thread, here it is again what I posted on the first page:

I would give Russ J. a call and get his opinion also if he does not answer here in a while.

Not all direct drive pumps will pull from a tank, he can tell you which ones will. There have been guys that built systems and find out that those certain pumps will not pull from tanks so they had to have hoses connected all the time.

If you read this then you would understand what is being talked about here.

There are guys that have 2 or more direct drive machines pulling from a tank but they are the direct drive pumps that will pull from a tank.
Again, not all direct drive pumps will pull from a tank but some will.
Again, that is why I mentioned about asking Russ J. about which ones will so he does not buy the wrong pumps.
 
I've been picking up quite a few pressure washers lately, for cheap. Three direct drive and one belt driven.
I found a belt driven General pump machine for $75 which only needs new packing, got that one about a month ago.

In the meantime, I found two Honda GX390's with direct drive pumps. One has a comet pump, 4k psi and 4 GPM, came with a 10GPM gun, 50 feet of non-marking goodyear hose, and was in brand new condition. The owner had used it for his beach house twice, and I picked it up for $225. I bought another GX390 today, and it has a cat 6DX pump, 4k psi and 4 GPM. Non in quite as pristine condition, but it only cost me $100.

My fourth was a Porter Cable machine with a 15 hp Kohler engine and an AR pump. This one had 50 feet of hose, gun, several lances, etc. Also in brand spanking new condition. Had less than 20 hrs on it. The man kept it inside his house and even gave me new oil and air filters for it. $300.

That's four machines for $700. Every one of these was bought off of craigslist. I definitely feel that I'll be able to come out ahead with these. The belt drive needs new packing, and a new muffler actually. Mufflers are dirt cheap. The packing will be a bit more, but I'll still be at less than $200 for a running belt drive machine.

I guess my point is that if you don't NEED to have two machines right away, then just be patient and wait for a good deal and you'll definitely come out ahead.
 
With the right unloaders and "T" 's you can connect some of them for larger gpm's for faster cleaning, running huge surface cleaners and rinsing huge areas fast.
 
Tony, it'll work. The AR RKV series is what I would recommend. 4, 4.5, 5, 5.5 gpm are all available.
 
belt drive frames, with belt-guards and pulley-kits

You all just TOIL over this, don't you !??!

Russ is right, as usual.. direct drive will "work"
..sucking water from your holding tank and all..
Just remember..
HOW you PLUMB the pump is where you get reliability..
DUAL-feed that pump, with 3/4" lines off a 1" main line,
BIG filter, etc.

I've gone on and on about that, and the differences between direct drive,
gear reduction, and belt drive.. here's an update..
more gear-reduction systems have recently passed through our service dept,
and we've upgraded several direct-drives to gear-reduction
..after the owner realized that seals, ceramics, valve-seat-damage,
and shaft-repairs are eating our lives away along with profitability..
Gear-reduction versions eat far fewer seals, slower speed pumps eat fewer ceramics,
and they don't seem to grow cracked valve seats,
..but when you DO have a pump issue,
those #$*&#!! shafts STILL get stuck together !!
To help minimize the chattering that occurs,
we weld the shaft-keys at the tip of the shaft,
and we coat the shafts on assembly with Anti-Sieze compound, to stop corrosion, but still..
..When you NEED the pump off the motor shaft of either a direct-drive
OR gear-reduction version,
and the shafts are stuck tighter than teenagers in love..:yikes:
That system is down for ANOTHER expensive, "lost the cleaning-job" day.
And I HATE working for free through "special discounts" .. aka.. spending extra-hours
squirting Liquid wrench at the shafts, and prying-mounting-flanges-to-pieces,
and selling replacement parts at near cost.:thud:
BELT DRIVE RULES !!
Absolutely, .. hands down !

Did I mention belt drive frames, with belt-guards and pulley-kits are available ?
..in several combinations !??
.. nuf said.
And if you STILL choose to be cheep.. :kma:
don't be a whiner.
 
So Jerry you are saying that if someone wanted to build their own belt drive unit, you can supply them with the frame with holes already drilled so they bolt their own motor and pump on there, attach belts and hardware and are ready to go?

It would be nice to have a supplier that could offer those, not sure if all vendors out there can do this or if they don't have the templates for the holes already made or not.

Thanks Jerry
 
I have a few "standardized" frames available..
matching pulleys "and all" can be time-consuming,
but Yes, I am going to be offering frame kits.
E-mail for more details, and include YOUR engine-pump combination.
 
The way i was told here was that any direct drive pump will draw water from a tank with the proper unloader. But (Russ) The man has spoken!
 
I hooked up my "cheapie" today. It works like a charm. The only thing wrong is I think I have a bad pressure gauge because its reading about 500 psi directly on the pump when it's clearly getting more than 3000 at the tip.

I haven't done the bucket test, but with the 13hp it seems I'm getting the 5.5 gpm as advertised. It looks almost exactly as strong as the 6gpm I've been running but with a lot more pressure.

It was so small and light I ended up mounting it on the back corner of the flatbed instead of on the lift.

Now I've got
a) 1500 psi 6gpm hot and
b) 3500 psi 5.5 gpm cold

I'd like to plumb them to the same reel (300ft+)right there at the truck - then split them back off at the end so two guys can carry up 50ft each and work 100ft apart at the same time.

Being that I've got 3/8 hose on the reel (and no, I won't switch to 1/2 inch - do you have any idea how much 1/2 inch weighs when you are trying to pull it up 10 stories?)

How do I go about that? Or am I dreaming again?
 
Put a Coupler on the hose reel swivel. and just plug in from whatever PW youll be using.
 
Tony's original question was about "Long-Term-Low-Cost"
in the difference between direct drive and belt drive..
That involves HOW to make them reliable,
How to keep them serviceable,
How to minimize downtime.
and how you manage the "maintenance".

Here's a direct answer, based on 25 years of actual "paying-attention" experience,
in the service department..

Direct drive pumps.. were designed to be pressure fed..
they can last 4 years between seal kits, especially electrically driven,
with low-water-shutdown, and "Delay-Off" shutdown.
IF plumbed with a high-volume bypass, IF properly treated.
..that's only about $275 in pump parts n labor in 5 years.
..just keep your fingers crosed you can separate pump from motor when you need to.

Tank fed..
I've seen direct drive pumps get 2 years on a set of seals, but the average is only 12 months,
because the tank is usually half full, or much less.
On "repair day", expect to also repair shaft-key damage,
and replace a check valve set every other time..
that's over $1000 for 5 years, IF the pump isn't tossed at the "bone-yard" before.
I didn't even add the possible cavitation-damaged ceramics or cracked head at a valve-seat.
... that can be another $500.

Belt drive..
I've seen 5 years out of a set of seals, used several days per week,
but 3 to 4 years is more reasonable,
to a system that isn't always getting the "perfect water supply".
Valve replacements every 4 to 5 years.. 3 years is most common.
Shaft repairs are "somebody else's problem".. but do add a set of belts.
Cost for 5 years, tank-fed, on average..
$ 375. including labor.
..and the pump can last 12 to 20 years, depending on how you treat it.

These numbers are based on a 5gpm pump with competitive parts pricing..
Newer models are coming out with more "model-specific" kits..
with "elevated prices". Some are now double or triple the above costs !
..Stick with the AR and Comet models Russ and I recommend..
Especially Comet HW and RW series,
AR's RK and XW series, or
General's good ol' TS2021 and EZ series

Also,
I didn't add unloader valves to the above numbers..
high-speed pumps eat TWICE the unloader-valves, or more ! Cavitation KILLS !

Again.. Respect the tech..
Follow our lead to "long-Term-Low-Cost"
 
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I don't get much argument..

Gee..
If my wife asks why I spend so much time in the blogs,
should I tell her I don't get much argument ??
:blink:

:rotflmao1:
 
You can combine them into one line and split them again on the roof into two lines. If you don't "balance" the lines on the roof you will get big fluctuations in pressure and volume when one of you lets off the trigger.

To balance them you will need to install a down steam injector sized to the appropriate gpm you are trying to achieve at each gun. This restriction will only allow a certain amount of water down the line to each gun (like a pressure nozzle). All the excess water will be sent into bypass that is not being used by each gun when the triggers are released (with a trapped pressure unloader, flow unloaders will not work with this setup). Typically the injectors will be installed at the T where you split the lines, but you can place them farther down if you like. I recommend the Super Suds Sucker as it is more precise with the different orifices it comes with.
 
love those variable-venturi ST61 chemical injectors !

Great tip, Paul !
Maybe the ST61 injector with the variable ventui would be even better,
since you can adjust the flow through it.
...and they are really low cost. :)
 
love those variable-venturi ST61 chemical injectors !

just get a pressure guage in after the injector to set the flow right.
they too..
... are really low cost. :)
 
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