I have mechanical disc-brakes on my mountain bike. I am wondering whether it is possible to have the brakes activated without me pressing the levers.
I test-rode a trike that had a parking brake lever. There was an extra button underneath the housing and when you pull the lever, it clicked in and holds brake lever locked down.
To release parking brake, you squeeze the lever a bit more and the button pops out.
The brake is to help you load your cargo with the trike not rolling away.
Mechanical disc calipers typically have an external lever which is pulled by the cable to move the pads onto the rotor. You can try using something like a zip tie to pull and fix the lever.
You can also just wind in the barrel adjuster on the cable but you’d need to re-adjust the caliper when you release it.