Posted by Clint Dixon [108.162.216.33] on Saturday, January 09, 2016 at 12:49:28 :
In Reply to: Re: What about a crankshaft PTO? posted by Chewie [162.158.255.6] on Saturday, January 09, 2016 at 10:04:35 :
There is very little room between the crank pulley and the radiator to locate a crank driven hydraulic pump. If one wanted to have a belt driven pump, the most logical place for it to be located would be below the crank, in order to use a short belt, but the frame crossmember is right in the way. To the right is the lower radiator hoses, to the left is the generator, and directly above is the water pump. To miss any of these would require a long belt and then there would be the problem of belt slippage when running a hydraulic pump.
The better alternative would be a shaft drive directly off of the crank shaft. This would mean extending a PTO shaft through the lower tank of the radiator. This limits the diameter of the shaft to about .875 inch maximum. There would have to be some sort of provision for flex in the shaft between the crank pulley and the radiator in order to allow for engine float. The Monroe setup used a light-duty Morse 301 series coupler 302 in this location and there is barely room for that. Some firetrucks and other specialized equipment used a cross and trunion u-joint in this location. This all has to be disassembled in order to replace the fan belt to the water pump.
Once through the radiator, the winch cable is in the way for a PTO shaft exiting straight forward. There may be room behind the winch for belt sheave, to direct power around the winch, but again we are back to the problem of belt slippage. There is very little room in that location for a hydraulic pump.
Add to this the problem of how to connect a u-joint or flexible coupler to the crank pulley. A redesigned nut to hold the pulley to the crank with provisions to drive a shaft will unthread when under load. The crank pulley is very thin and does not allow much "meat" to mount to. This all works marginally when attaching shafts that drive hydraulic pumps to lift cylinders and water pumps to fight fires, but to power a snow blower, this whole area could become a messy expensive weak link or "shear pin".
With either a crank powered PTO shaft, or the transmission powered PTO shaft, and no provision for a two stage clutch ahead of the transmission, one would need an overriding clutch somewhere in the power line before the snowblower. Otherwise, centrifical force of the snowblower would continue to drive the truck forward even when one depressed the clutch pedal.
Just my thoughts.
Junior
Follow Ups: