In Strategic Ops page 139 has a subsection called "how not to get on a gravdeck" it references "transfer cars" to get on and off gravdecks. But it's really just that reference without much explanation of how the car works. The rest of the section mostly focuses on the WHY, as in why you need/want something like that and not just jump onto a gravdeck moving at 3 miles per hour (give or take, depends on size of the grav deck) which it explains has a floor speed of 56 kph on a small grav deck, and a floor speed of 256 kph on the grav deck on an olympus.
Personally I struggle to visualize how that transfer car concept is engineered to work. I'm not questioning it, I just wish I had a model, or some art or a video, something that could help me conceptualize it.
EDIT: Found more, in the main body content of that page it says jumpships and warships must use a "subway system" of transfer cars paralleling the gravdeck's track.
It says space stations are more likely to use long elevator spokes to a slowly spinning hub. Because the station can be built without worrying about getting in the way of a KF drive, ammo feed, power lines, data lines etc.