Direct Drive question

Tony Shelton

Tony Shelton

BS Detector, Esquire
Has anyone ever done the math on direct drive vs belts in the long run when building from scratch?

For example, I've got an extra 11 hp motor now. I'm thinking about buying another motor and throwing a EZ3045G (general under $300) the two of them.

Why?

Because of the compact size I can fit both of those on the equipment tray at the bottom of my lift and have the option of one gun at 4.6 gpm or 9 gpm OR two guns at 4.6 and I don't have to waste fuel when I only need the one. I still have the hot water unit on the truck for a third gun with heat if needed.

Let's say I spend $1500 (chinese motors) for the entire setup including unloaders, tee, and other plumbing. How long should the direct drive last vs belt drive? Will I come out ahead over 5 years?
 
The local Pressure Pro/ All American/ Landa dealer told me that the old "Direct drives won't last" mantra is outdated. He said that the new direct drive pumps are engineered to be durable in a directly-driven setting and last much longer than they used to.
 
I can't give you a time frame in years...but I can tell you that I sell noticeably more direct drive replacement pumps that I do belt drive replacement pumps
 
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.

I am sure that the quality of direct drive pumps is getting better just like most other things out there but belts help with the vibration and heat which both will harm pumps over time.

Another option is the lovejoy coupler. Good heat dissipation and some of the vibration is lost in the rubber spider that is in-between the engine and pump.

I was told by the Landa, Hotsy and Alkota mechanics that the belt drive pumps will outlast many times over the gear drive and direct drive pumps. With the gear drive pumps, it is usually the gear box that goes out first I am told, this was in the last couple weeks when I was there having equipment worked on.
 
The 2nd machine I just put on my truck is gear driven. I'll wait til the gear drive gives out then convert it over to belt driven like I did my other machine.

If I do that I'll make the drive to Tucson and let Tom do it for me though this time. He did a great job converting his machine over to belt drive.
 
Gear drive increases initial cost by at least 40%. If I use that money for an extra couple of pumps I can keep a spare on the truck and change a bad pump in 5 minutes or so.

I'm looking for some numbers.

Let's take a 5 yr scenario. Say I have to replace the DD once every year that's $1500 in five years. Say I have to replace/rebuild the belt drive every 2 years thats about $700.00. Then the question becomes, is it worth $150.00 per year extra to have a pump I can fix in five minutes.
 
There is a local guy I service who has the 13 hp direct drive units, he runs them 5-6 days a week and has at least 4 crews using them. For his application they seem to last quite well (most are over 5-8 years old). Dollar for dollar I would say they will last you as long as a belt or gear drive if maintained. Belt or gear dive are usually better (when built right) but don't be scared of a direct drive pump, for what you do I think you would be happy with them
 
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
 
Tony Shelton said:
I thought I would be ok with the feed because the tank is approximately a foot higher than the level of the pump.
Click to expand...


I would assume the hydrostatic pressure, from the tank being a foot higher than the inlet, should have the same pressure or a bit less, then a garden hose, should be fine then
 
Timothy said:
From memory only:

A one foot high column of water produces 4.3 pounds per square inch.

YMMV
Click to expand...

10 feet of water, produces 4.33 at the base

so 1 foot would equal 0.43 psi

but his tank isnt flat on the ground it is 1 foot suspended, so that is an added factor is psi at the base, not by much though,

so a standard 3-4 ft tank would produce

3 feet = 1.29 psi
4 feet = 1.72 psi
 
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
 
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