I had a pull-back toy car like that when I was a child, probably mid to late '70s. They have a built-in torque limit to protect the mainspring and gears from winding too tightly, that is what makes the ratcheting sound when the tricorder is closed.
The cars are really quite clever and complex. When you pull them back, not only is there the overwinding protection, there is also a mechanism that changes the gear ratio. So when you pull them back a given distance, say 1 foot, upon release, they are propelled forward by the spring for a much longer distance, say 5 or 10 feet. Even after the spring unwinds, they continue to coast.
This is why you hear the ratchet sound every time the tricorder is closed: when opening, the mechanism runs in "forward" mode -- low torque but long running time (in the car; not very long in the tricorder, though, thus the mainspring doesn't get to unwind very far). But when the tricorder is closed, the mechanism shifts gears into "pull back" mode. In the car, it would take much more effort to pull it back than the motor pushes it with, but consequently, you only have to pull it back about 3 feet to wind it from fully run down to fully wound up. In the tricorder, every time the tricorder opens, it only "unwinds" maybe an inch worth of rolling distance, but when someone closes it, due to the gear change, they're actually trying to wind it up several times the amount that opening it allowed it to unwind. That's why it makes the ratchet sound every time the tricorder is closed.