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TECH TIP TUESDAY – LINE LOCK NOT OK FOR PARKING BRAKE!
WE HAVE SEEN – WE HIGHLY RECOMMEND AGAINST IT!!!
The use of a “Line Lock” for Parking Brake!
We recently had a rig come in with an issue of it’s “parking brake” not holding the heavily cladded overland equipped 40-Series Toyota Land Cruiser in a “parked position.” Upon inspection, the rig is using a “line lock” for a parking brake. The diagnoses is that just after a few minutes, the solenoid line lock is heating up and can no longer hold the desired pressure required to hold the weight of the vehicle.
We tested to see how hot the electrically driven solenoid was heating up to and releasing pressure. It’s all a sliding scale of pressure heat and time. Also, this is creating a direct drain on the battery when in use.
Upon further investigation, the particular line lock in use is for supplemental & temporary brake holding. Even these “heavy duty” industrial line locks are to be used in conjunction with a vehicle’s mechanical parking brake. These line locks perform as operational parking brakes only such as a dump-truck stopped to dump a load. Line Locks are not intended for prolonged “unattended” parking, thus, this is not the optimal parking brake solution.
The Line lock was initially and only used as a temporary devise to lock the front wheels for some smokey burn outs! OK, there are industrial applications as well, but again, only for temporary use. Lets “lock-in” further on this “line lock” apparatus!
Lets talk the fun “line lock” stuff first – DRAG RACING!
Line locks are often used for burnouts by fully locking the front wheels and then engaging the gas pedal and disengaging the clutch pedal. This makes the rear tires spin but keeps the car stationary. In drag racing, the manual transmissions allow drivers to control the amount of power transferred from the engine to the wheels by manipulating both clutch and throttle inputs, allowing vehicles to accelerate quickly without losing traction. However, launching a vehicle requires simultaneous gas pedal and clutch pedal inputs, preventing drivers from manipulating the brakes with their feet.
Without brake input, drivers staging their vehicle at the starting line would roll if the clutch was slightly engaged. If the driver’s vehicle rolled across the staging line before the start of a drag race, the driver could “red light” and would disqualify them from that race, nullifying the results or being declared DNF or a “Did Not Finish” which is not good!
Lets talk the work-world or industrial side of “line lock” stuff!
Mico is a manufacturer of Line locks and other brake products for a wide range of industrial and commercial usages.
The above industries look like fine examples of commercial and industrial use! But too, right there on the Mico’s “Brake Lock” page, they state, “MICO® Brake Locks are for supplemental brake holding and are to be used in conjunction with a vehicle’s mechanical parking brake. They perform as operational parking brakes only and are not intended for prolonged parking. There are several brake lock solutions available for single, dual, split, or anti-lock brake systems. The MICO portfolio includes electrohydraulic, dualock, lever, twist, cable actuated, and electric activated. MICO® Brake Locks are ideal for construction, mining, agriculture, material handling, multi-stop delivery and recreational vehicles. They fit most medium and light duty trucks equipped with a hydraulic braking system.”
In most vehicles with rear drum brakes, two emergency brake/parking brake cables actuate the brake drums mechanically, but with much less force than is available through the primary hydraulic brake system. It is common for this type of system to work well when facing downhill but be unable to hold the vehicle stopped without using wheel chocks when facing up a steep hill. An improvement over stock parking brakes is useful for off-road vehicles such as tractors, tow trucks, 4×4’s, construction vehicles or any drum brake vehicle on ice or steep terrain. Some manufactures use a transmission brake which locks the entire drivetrain.
In order to park by using the primary hydraulic brakes, a hand-operated valve is added to lock hydraulic pressure in the brake line. For parking using the brakes on all four wheels, two valves may be necessary. Any leakage at the brake cylinders will reduce pressure in the line and release the brakes. For this reason, line locks should only be used temporarily.
This is what is in the customers rig:
Now… We get it, we want our rigs to stay put!
We know it’s an “issue” in keeping our 40-Series Land Cruisers parked!
With all this “stay parked mystery” of our FJ40’s, maybe this is truly the reason Toyota has part number: 09184-00010 designed specifically for such task and along with safely changing tires.
Guess we will need to make a para-cord tether-kit to go from chock to door handle and an additional jet-tag keychain “WHEEL STOPPER ENGAGED” reminder so we don’t forget we have our factory folding Toyota Wheel Chock’s holding us in the stopped position! We are in no way making fun of the customer, but making light of the situation at hand as we know there is no “ultra-parking-solution” for FJ40’s. Yet…
PS: Don’t keep your rig’s manual transmission in gear while sitting at the stop light.