Quote:
Originally Posted by JFKinator
I guess another question I could ask is if any of these shifters would be able to work with a PTO or be able to be modified to do so?
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Modifying any of the COTS shifting gearboxes into a PTO is relatively straightforward depending on what you're shooting for. This year, 341's gearboxes are nothing more than a WCP SS shifting stage* repackaged into a custom box.
Basically what you're doing is taking the shifting stage from any of the shifting transmissions, putting it inline/parallel with the transmission for the drive, and then engaging/disengaging that shifting portion as you need to transmit power to whatever mechanism. In our application, we have three CIM motors each with a 12T Pinion driving a 72T gear for a 6:1 total reduction. The output of this shaft then drives one of our drive wheels with through a series of 50T gears for a 1:1 reduction (can be changed by swapping gears). On that same output shaft, there is a 60T gear that drives a 60T Dog Gear that is the same as used in the WCP SS Gearbox. The 60T Dog gear is on a standard WCP SS output shaft - but instead of the output shaft having two different gears on it (high and low, usually a 60T and 45T) there's just the 60T and a brake. Basically, when the 60T gear isn't engaged, the PTO shaft is locked, but when the PTO is engaged, the PTO shaft is essentially a mirror of the drive output shaft.
If you wanted to do a two-speed transmission with a PTO, it's more or less the same as what I described above, although, you'll have two shifting stages. If you wanted to, you could have the CIM's drive a cluster shaft that drove both shifting stages and then devote one to the drive and other to the power take off... Or you could drive a second shifting stage off of the primary shifting stage and do some neat tricks like having a PTO output with a high and low gear - this lets you drive a mechanism at two different rates, high speed for extension, low speed for retraction and stuff like that.
One thing to keep in mind when designing a PTO for whatever mechanism is whether or not some portion of it will need to be able to be put into neutral and/or held into position. A lot of PTO's will have some function that will allow the drive to be put into neutral to keep the wheels from spinning while the PTO is engaged, but it isn't always necessary. An 'easy' way to add a neutral function into a standard PTO setup (or two speed, if you wanted) is to replace the standard two-position piston with a three-position piston. The third position should land somewhere between the extended and retracted position of the piston which would then allow your transmission to go into a configuration where neither high or low gear is engaged.
* Shifting stage being the shaft that has the shifting hardware, whether that be dog gears, balls, etc. Remember that a shifting shaft can have two different gears on it to shift between ratios, one gear and nothing for an engaged and disengaged setup, or any other combinations of brakes/gears/nothing.