
never heard of this before nor did I ever slam my 4X4 into gear this way

Sorry but I have to completely disagree
Well I guess you are going to learn something new todayabout jinma tractors... What kind of 4X4 are YOU refering to. My Jinma 284 tractor and every toyota 4X4(any 4X4 that I can recall) I have ever used works this same way, providing the hubs are dialed in, and you are not spinning the rear wheels hard when you shift. Ever heard of "shift on the fly" The toyota transfer case has the advantage of helical cut gears with a beveled leading edges, so they pull in quite easilly from almost any orientation.
The jinma does not. IT uses a pair of 3 toothed pawls to couple in and out of 4X4. Imagine a piece of pie cut into 6 pieces with every other piece removed. This mates with an identical part. Since the parts are not tapered at the front, they must be rolled into alignment.
In the case of the jinma tractor when you work the 4X4 lever you are sliding part number 35 in this diagram.
http://johnstractor.homestead.com/files/ClutchHouse.jpg The shaft it slides on is HARD COUPLED down to the front driveshaft via the transfer case gears.
Hard to read in this pic, but I think it is part 42(lower left) is the part that 35 in the above pic mates with.
http://johnstractor.homestead.com/files/DriveGear.jpg IF you look carefully, you will note that the part is hard connected to the front end of the shaft that runs straight thru the gearbox and into the drive gear in the rear differential. It is in those driven gears that engine torque gets applied to the system. So both parts are hard coupled to the axles, and no clutch to be found anywhere. just like the transfer case on most any 4X4 vehicle, located at the OUTPUT of the transmission..
That means as long as the wheels are not spinning the 2 parts are turning at nearly the same speed, but not exactly due to differences in all the gears involved as well as tire size. That is why you don't run 4X4 on hard surfaces. In soft earth, these differences are absorbed by wheel slippage. On hard surface the differences are absorbed as aded heat/wear/breakage in the drivetrain...
While rolling ahead, apply gentle upward pressure on the 4X lever, and when the pawls align, it will slip right in. Turning either left or right may speed the process. Occasionally the parts will be in alignment and it will just pull right in, but there is no guarantee of this...