I took my model T into one of those VTNZ testing stations as in Ted's post. After explaining to them it had a transmission brake they were somewhat unsure how to check. Finally, they sat some sort of 'G meter' on the floor, had me drive it as fast as I could in the space provided, and on their command to apply brakes. Dunno what the G meter said, but it passed!
So, then I told them I'd bring my new Ford in for a Warrant of Fitness check [1935 Ford]. When I set up the brakes on that thing, I use a gravel road and adjust each brake until all skid marks are the same length. They put it on the brake machine as in Ted's pix. Result - fail!! If I applied the brakes. both gauges would go up the same amount, indicating even braking each side. They insisted however, that rather than 'jumping' on the pedal as I do, to just gently apply pressure to the pedal, and each gauge would then tell a different story. I couldn't explain there is no/very little servo effect with these brakes, they didn't wanna know. I finally got my WoF after a coupla rechecks, but really, the guys that work there are a bunch of dickheads. Why could they not have used the same testing method as they used on the T?They do not understand the indiosynchroses of this old iron. So, as KiwiTony explained, most of us guys now take out old vehicles to our 'favourite' issuing person, someone who can use common sense judgement.