Starting to look at pump upgrades… noticed that Udor gives power requirements in both gas and electric HP based on if it’s a solid shaft or gear reduction set up. Photo as an example… the MKC 18/24-S is the exact same pump as the MKC 18/24-GR it just doesn’t have the gear box? I already have a 2.2:1 gear box, so if I can just buy a solid shaft pump to save some $$$ I’d prefer to do that.
The follow up to that is also what rpm pump to get… am I correct in thinking that with a 2.2:1 gear box, running my engine at 3600 rpm, I would be spinning the pump at 1636 rpm. This would mean that with a 1450 pump I would be exceeding the rating, which would increase gpm at the expense of overworking the pump and shortening its life? On the flip side for the 1750 I would be running below it’s rating, which would mean I may not get its rated gpm but I wouldn’t be working the pump past it’s max and it should last longer? Is that how it works? Is there a better gear box ratio to get?
So try to get a 1750 rpm pump, different ratio gear box, or go belt drive (rather not because of space/layout in truck)? Seems almost every gear driven pump comes with a 2.2:1 or 2.24:1 gear box so they would all be over spinning the pumps? I’d have to double check the specs on it, but my current 5.5 gpm udor is probably over spinning but still pulls water… maybe it’s just “close enough”.
The Allison 6.8 gear drive pump I run is just a 1450 rpm Comet 5.6 that is rebranded. It pulls from the tank with no issues but my gearbox crapped out last summer. I believe my key was too short & walked until it broke at 1/4 inch or so & cracked the hollow shaft (the gearbox key way is much longer than the one on the engine shaft). New gearbox and a much longer key seems to be working well. Engine rpm will decrease under a load, so I get 6.75 with soap nozzles & 6.25 with pressure nozzles. Keep an eye on the classifieds for those barely used rigs if you’re not in a hurry.
I get that, but I already have the gearbox/skid set up that works for the footprint in my truck… I’d like to stay with it, but open to alternatives if they really are that much better.
Gear boxes from yesteryear had their issues, which I believe is a lot of these guys only experience with them, and it put a bad taste in their mouth. I’ve owned one of each and would take a gear drive every time because it works better for my layout and I’ve yet to have issues (knock on wood).
William has been in this PW business as long as I’ve been window cleaning, he’s got some serious experience under his belt so curious what he ran into.
Apologies, I received a notification that you had replied to me. I know IBS knows his stuff and I don’t want to speak for him, but I vaguely recall him mentioning that his one gearbox experience was with a poly chain gearbox. Hence the reference to older gearboxes having reliability issues. I haven’t heard of any recent issues besides the shaft punching a hole through the housing (user error for not using spacers) and excessive wear on the key shaft caused by gear lash during startup. All that to say, gear boxes are on par with belt drive in my eyes and work better for my set up from a space constraint. There are more ways to skin a cat though so use what works best for you.
