Sorry about the boulder, and the PT. If you didn't see this in the news, it could be worse;
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What I loved about this almost Darwin award winner isn't that the first rock blew through the barn and blew it up,
or that the second rock stopped just before blowing the house up and managed to miss the car,
it was that there is a third rock off to the right from an earlier rockfall with moss growing on it.
Somebody intentionally rebuilt in the path of these rocks....
But back to the topic at hand. On my 1445 the motors are in parallel, i.e. Left side pumps tee off the same supply, ditto right side, with the small subtlety that there are cross connects of a small diameter hose LF motor to RF motor and LR motor to RR motor, at least on my 1445. I would point out that since it all is plumbed back into the same pump chamber, I don't know how much one gains via the cross connect, but since there is still motion even with one wheel in the air, there is a certain amount of dynamic resistance even without a wheel load.
Given the hydraulic plumbing, I suspect that anything other than four identical motors will give you issues. So, if it were me, I'd either replace it with a PT motor, or buy four matching ones of approximately the right size. (Chance to trade up or down to gain torque or speed). Top speed can be converted to rpm, but I don't know how you would get the displacement of the motor. Again, if it were me, I'd skip the oddball motor with a great deal somewhere because when the dust settles, all those little adapter fittings add up.
If you don't want to do that, I'd take the motor into a couple of local hydraulic shops and see if someone recognizes the design, and can interpret what is left of the ID numbers on the motor. The manufacturers make so many variants on the motors with different seal types, shims, and configurations that it is going to be tough to get an exact match without having an expert disassemble it and work out what is actually inside. Of course, there is a price for everything.
J.J.: do you have a link on a standard operating procedure on how to do that displacement measurement? It would seem to me that one would want to fill the motor, turn the shaft a few revolutions and then measure the displace oil for one revolution. Even so, the method seems open to all sorts of potential errors.
I did find this
video link on how to do it, but it requires complete disassembly of the pump, so it didn't seem that useful.
All the best,
Peter