A beadlock or bead lock is a mechanical device that secures the bead of a tire to the wheel of a vehicle. Tires and wheels are designed so that, when the tire is inflated, the tire pressure pushes the bead of the tire against the inside of the wheel rim so that the tire stays on the wheel and the two rotate together. In situations where tire pressure is insufficient to hold the bead of the tire in place, a beadlock is needed.
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| Bedlock 8x16 |
There are several styles of beadlocks. For 4-wheel drive vehicles, a ring with a number of bolts around the circumference is used to clamp the tire to the wheel. For motorcycles, a rim lock or bead stopper is a curved plate tightened by a single bolt. For both 4-wheel drive vehicles and motorcycles, a different style of beadlock can be used that is similar to an inner tube which is inflated to press the tire against the wheel.
Bead lock may also refer to a product used to secure a swimming pool liner into the pool liner track installed on many above ground pools. It has a wedge shaped edge on the front of the strip. When installing the strip, it inserts just above the pool liner bead. It then locks the liner into the receiving track.
Purpose
Air pressure within a tire forces its beads against the wheel rim and normally ensures that the tire and rim rotate as a single unit. In general automotive situations, a tire's air pressure is sufficient to withstand dislodging and rim-slip forces experienced during, respectively, hard cornering and acceleration (including negative acceleration or "braking"). Low tire pressure therefore poses the hazard of enabling sudden loss of air, loss of control, and even a rollover during hard braking or an evasive maneuver (in addition to generally promoting excessive tire heat and future failure). Modern automotive tires have a soft rubber formulation at the beads to help maintain good rim contact, so special bead-lock means are not required.
High traction is desired for tires for automobile dirt track racing, off-road racing, off-road vehicles, and off-road motorcycles, so their tread is therefore coarse. Nevertheless, some riders will lower the tire pressure to cause the tread to spread out and create a larger contact patch. This practice can create a safety hazard, as there may not be enough pressure to adequately secure the tire beads to the wheel. Reactive ground forces push a tire to one side or the other, especially the outside rear tire of a racing vehicle when it is turning in a corner of a track. This could cause a bead of the tire to come off the rim completely, or enough to cause partial loss of air. It is also possible for the tire to have more traction on the ground than there is friction between the tire and rim. In this case the wheel would slip around the tire beads without turning the tire. Beadlocks, of one form or another including adhesive, are therefore used to keep the beads of off-road tires firmly seated and prevent slip, even when inflation pressure is low.
