Gear Box VS Belt Drive

30 in the pump, 90 in the gearbox.
 
Here is what I tell my customers. - The larger the pressure washer, the more often you clean, and the longer you spend cleaning each
time, the more you need belt drive.
Warranty claims on direct driven pumps are higher than on similar pumps that are belt-driven.
Belt driven pumps usually operate at lower RPM with a larger oil capacity. A pump coupled
directly to a motor or engine places strain on the motor and mounting bolts and will absorb extra
heat and vibration that may shorten the life of the unit. Many direct drive pumps do not really
contain enough oil to do the best job coping with the extra heat. With direct drive, anything that
happens to the motor happens to the pump and vice versa. Even “high quality” direct drives will
require more maintenance, may be more difficult to repair (pumps nearly impossible to remove
from engine or gear shafts are common), and may require major repairs more often.
Improvements such as gear reduction drives, shock absorbing mechanisms and more precise
machining, have made direct drives better, but at a cost that begins to rival belt drive. For
continuous or frequent use they cannot overcome the inherent advantages of a quality belt drive.
 
Flipper said:
Here is what I tell my customers. - The larger the pressure washer, the more often you clean, and the longer you spend cleaning each
time, the more you need belt drive.
Warranty claims on direct driven pumps are higher than on similar pumps that are belt-driven.
Belt driven pumps usually operate at lower RPM with a larger oil capacity. A pump coupled
directly to a motor or engine places strain on the motor and mounting bolts and will absorb extra
heat and vibration that may shorten the life of the unit. Many direct drive pumps do not really
contain enough oil to do the best job coping with the extra heat. With direct drive, anything that
happens to the motor happens to the pump and vice versa. Even “high quality” direct drives will
require more maintenance, may be more difficult to repair (pumps nearly impossible to remove
from engine or gear shafts are common), and may require major repairs more often.
Improvements such as gear reduction drives, shock absorbing mechanisms and more precise
machining, have made direct drives better, but at a cost that begins to rival belt drive. For
continuous or frequent use they cannot overcome the inherent advantages of a quality belt drive.
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1: Please explain why a pump that is driven by a belt can turn lower RPM's vs that same pump that is driven through a gearbox. 2: I agree with your statement " with direct drive any thing that happens to the motor happens to the pump" which is why I don't like direct drive. We are talking about gear reduction boxes not direct drive. Thanks for your input Philip!
 
JDhomeservices said:
For some reason, I was under the impression that gearbox driven pumps needed more engine HP to produce comparable PSI/GPM to a belt driven pump. Kinda like adding a generator vs a 12v burner. Am I wrong about that?
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An achieved PSI/GPM does not come from engine HP, it comes from RPM,s. ANY and every pump requires a specific RPM to produce a specific PSI/GPM weather it's driven by belt or gearbox. It also takes a specific amount of power (HP) to achieve the required RPM"S to drive that pump weather it's driven by belt or gearbox. I don't think it takes much more power to turn a gearbox vs belts but it does take more especially when the gearlube is cold. As far as a generator is concerned it takes much more power to make 120 volts vs 12 volts because of the size of the generator components. I hope some one can explain to me why people think belt driven pumps turn less RPM's. An inquiring mind wants to know.
 
People think gearboxes spin at higher RPM's is because they are thinking direct drive. As mentioned gear drive uses the same pumps as on the belt driven setups, only differences are the foot print. I have only ever used or built belt drive systems as this is what I have read as being the best setup. Upon looking a little more into gearboxes and understanding how they work and what is different I still don't think I would switch or install a gearbox in one of my setups.

Part of the reason is cost, the gearbox is twice that of all the parts required for a belt setup.

Another plus I see on the pulley setup is that the weight of the pulley already turning will help with going from bypass to full pressure on a pump. The stress that has been reduced on both the pump and engine from this will help keep your bearings and oil seals in better shape and of course less down time.

If I had a gearbox I would not switch it out unless I had problems and didn't want to pay for another gearbox.

I wouldn't switch to a gearbox from a belt setup unless space became a factor either.
 
I have a gear drive (from envirospec) on an 18hp kohler and I was told the ratios in the gear reducers are a little off compared to how one would normally set up a belt pulley so I should run my engine rpm at 3200rpm to achieve the desired pump rpm, otherwise I would race the pump and exceed its spec rpms. My understanding is that this gives me my desired 5.5gpm but with less power available to reach higher pressures (ie I should not tip my wands to try to reach 3500 psi). One advantage has been that this engine sips gas at 3200 rpm and I expect longer life out of the engine.
Can anyone validate the ratios of gear reducers vs. belt pulleys? I bought this setup before I knew about the engine rpms and I think its a major disadvantage if its true, and I might not have gone this route.
 
JBurd said:
I have a gear drive (from envirospec) on an 18hp kohler and I was told the ratios in the gear reducers are a little off compared to how one would normally set up a belt pulley so I should run my engine rpm at 3200rpm to achieve the desired pump rpm, otherwise I would race the pump and exceed its spec rpms. My understanding is that this gives me my desired 5.5gpm but with less power available to reach higher pressures (ie I should not tip my wands to try to reach 3500 psi). One advantage has been that this engine sips gas at 3200 rpm and I expect longer life out of the engine.
Can anyone validate the ratios of gear reducers vs. belt pulleys? I bought this setup before I knew about the engine rpms and I think its a major disadvantage if its true, and I might not have gone this route.
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I'm pretty sure it is 2.176 on the gear boxes. So 3155 for 1450 and 3808 for 1750. I think these small engines run best and last longer at 3600 rpm.
 
Rance said:
1: Please explain why a pump that is driven by a belt can turn lower RPM's vs that same pump that is driven through a gearbox. 2: I agree with your statement " with direct drive any thing that happens to the motor happens to the pump" which is why I don't like direct drive. We are talking about gear reduction boxes not direct drive. Thanks for your input Philip!
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Let me make some general statements about the differences. While gear reduction pumps look similar to belt drive pumps, for the most part, that's it. When you take the two pumps apart, you will see that the gear reduction pump is going to have the same manifold, but the crank shaft, connecting rods, gears and plungers will be smaller. Thus they need to spin more to produce the same power. All of our gear reduction pumps have GR listed as the last letters of the pump model and are not interchangeable with our belt driven models. Lets take a 4 gpm at 2000 psi pump for example. A belt drive pump is spinning at 700 rpms while the GR pump will have to spin at 1125 rpms to achieve the same results. A direct drive then spins at about 2300 rpms. We use to offer many of our units with gear reduction pumps because they are better than direct drive. Very few other manufacturers were doing that, so in order to compete with everyone else selling direct drives, that is what we switched to as standard on our mid grade machines. We and every other manufacturer I am aware of, now only sell direct drive and belt drive. We still carry GR pumps in inventory and will sell a machine with one on it if someone orders it, but its been a long time since one left the loading dock. It is my opinion and one held by everyone in the industry that I have ever had the discussion with, that belt drive is the better choice over gear reduction.
 
Flipper said:
Let me make some general statements about the differences. While gear reduction pumps look similar to belt drive pumps, for the most part, that's it. When you take the two pumps apart, you will see that the gear reduction pump is going to have the same manifold, but the crank shaft, connecting rods, gears and plungers will be smaller. Thus they need to spin more to produce the same power. All of our gear reduction pumps have GR listed as the last letters of the pump model and are not interchangeable with our belt driven models. Lets take a 4 gpm at 2000 psi pump for example. A belt drive pump is spinning at 700 rpms while the GR pump will have to spin at 1125 rpms to achieve the same results. A direct drive then spins at about 2300 rpms.
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Finally the answer I've been looking for. It's the crank shaft, connecting rods, gears and plungers that are the different thus the RPM difference. Makes perfect sense. Thank you Philip for educating me on this issue. This information allows me (and hopefully others) to make a better decision on future pump set ups. Much obliged Philip!
 
What russ said. A direct drive is different than a gear drive. Lets take a udor 28/24 gr it is exactly the same pump as a 28/24 but with a gear drive added it spins the same rpm as the belt drive 28/24 for the desired pressure and gpm. Direct drives have to spin higher rpm's than belt or gear drives to get the rated specs, most all direct drives spin at 3200 rpm's to 33600 rpm's belt and gear drives spin between 1450 and 1750 rpm's.
 
Russ Johnson said:
Um...I can take a General TS2021 and mount it on a gearbox...

or an AR XW series. No difference in cranks, rods, pistons, etc..
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Russ your saying what I thought in the first place. No difference in the inner pump components? If the inner components of the pump are the same then that pump has to run the specific RPM's to produce specific GPM/PSI no matter if that pump is driven by belts or through a gear reduction box. Is that right Russ?
 
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There are 1450 rpm pumps and there are 1750 rpm pumps. Either one can be used with belt with the right pulley configuration. I think the gearboxes require a 1750 pump depending on the gear ratio. A 1450 rpm pump may be the best choice because it would be less wear and pull better from a tank. The pistons and crank sizes will likely vary between 1750 and 1450 pumps. Someone please say something if I am wrong here.
 
Flipper.. What are you thinking !??
IF you have an engine driven pump in your product line that runs at 700rpm belt driven..
that's a 5:1 ratio from a 3600rpm motor.. which means.. with a 3.2" pulley on the motor, the pump will have a 16" diameter..
Really ?? can you post a picture of that ?
..And your 2300rpm direct drive.. what engine are you running at 2300rpm ?? can you post that ??
These guys in here are trying to "understand" their equipment.. you seem a bit cornfuzing.
Here are easily interpretable facts..
a given pump has a bore and stroke, for a specific displacement.
example.. General TS2021 pump has a bore of 20mm, with stroke of if ..I remember correctly..12mm..
at 1450rpm it gives almost exactly 5.2gpm
If you have enough horsepower to force that through a #6 nozzle.. looking at your nozzle charts.. you see you get about 3000 psi.
The nozzle, nor the engine "cares" whether the pump is belt driven, or gear driven..
at the same rpm's.. you get the same results.
..except for what minimal slippage you get in the belts' transfer for Horsepower and velocity from pulley to pulley.
this slippage is not worth equating as long as you don't expect each B sized belt to transfer more than about 8hp.
..So..
Turning a pump faster, gives a larger and (generally) porportionate increase in flow..
and so.. your 4gpm pump at 700rpm will push .. at 1125rpm .. 1125/700 x 4gpm = 6.43gpm .
..like Russ said.
Guys, start READING the spec sheets that come with your pumps.
there's a lot of common-sense in there..
If a pump has the same bore and stroke as another pump, it will give the same flow-rate at the same speed
..no matter what brand it is.
Also.. hopefully, there's no longer a question about which is better..
getting the pump away from the engine's heat and "shaft-banging-pulsations" is better.
and using a slower-speed pump is better, as long as you don't have to pay for a 16" pulley and the enormous belt-guard that would house it..
 
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