Re: Gas power to PTO power
If the old motor was 1800 then one will have to basically go 3 to1 if the motor was 3600 then about 6 to 1 or a tad more.
figure out what the old motor or engine ran the pump at and divide that by the 540 and that is what one will have to step it up, so and then use a large enough small pulley to grip the and handle the HP of the unit, for example you say 3600 and need 6.6 to 1 say we put a 18" on the PTO the pump would be, 2.72" or close to that, for running the pump at 3600, if it is industrial like you said one it be speed reduced all ready so first you need to know what to run the pump at,
Unless one can use surplus parts by the time you get a PTO shaft, bearings, and pulleys and belts, and frame my guess is to buy new your costs are going to run in the $300 to $600 dollar range, (and if the replacement engines, is $2000 I would think you should consider a double to triple belt pullers and the cost could increase greatly, as your most likely dealing with a 16 to 25 hp engine, and a B belt is more or less a 8 to 10 hp range, (especially on the >3" driven pulley).
what would it cost to rebuilt the other engine?
As far as making it PTO drive it is most likely easy ly do able,
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If your going to three point or trailer mount it consider a tank on it for remote use, so one would not need a hose hooked to it,
pto pressure washer - Google Search
It appears that many of the manufactures use a gear box for the speed increaser, (may be possible to ding one using the same pump and buy the gear box and simplify the building).
