a couple of the tow trucks we service at my shop use the line lock for the e brakes. up here e brake cables dont last too long before they stop working so this is a much more reliable system.
derek
Just to clarify here so some goof reading this ends up doing something stupid:
There is a difference between Emergency Brake (eg. E-brake) and Parking Brakes.
A Parking brake is used to keep a stopped (parked?) vehicle from moving. A line-lock Parking brake would be excellent for a tow truck -- especially when the truck is pulling a vehicle out of a ditch. Over time a mechanical, cable-driven emergency brake would suffer from water damage and become unreliable. A line-Lock Parking brake would not be prone to a slow failure and would work as good as the braking system itself. And, it could be set up to lock up all four wheels.
Heck, a line-lock parking brake on the Electronic News Gathering (ENG) vans at work woul;d benefit from line lock parking brakes. If wired properly, it would be danged hard to move a truck while the transmitting mast is raised and the line locks were engaged.
An Emergency brake conjurs up the idea of plummeting down a steep grade trying to stop a vehicle with bad hydraulic brakes. You grab on the handle, pull and pray. Line locks would be pretty useless at this point as emergency brakes.