I thought a line lock went on the front brakes, used for drag racing so you can lock the front wheels and spin the rear to warm up your slicks. Never seen one used in the rear wheels...... unless you are talking the old Mico-brakes like were used on milk trucks. I do not believe those were not designed for use as a park brake either though.
I thought the same thing,
We just disconnected rear brakes (temporarily)
