With no explanation, label text_A→text_B with either "not_related" or "related".
text_A: Chris Pérez is the backup guitarist for a Tejano band.
text_B: Locking hubs , also known as free wheeling hubs are fitted to some -LRB- mainly older -RRB- four-wheel drive vehicles , allowing the front wheels to rotate freely when disconnected -LRB- unlocked -RRB- from the front axle .. four-wheel drive. four-wheel drive. This is done to reduce the mechanical resistance of the front-portion of the drivetrain when four-wheel drive is not in use .. four-wheel drive. four-wheel drive. The hub , along with the wheel , is designed to engage -LRB- lock -RRB- onto the axle , to be powered by the drivetrain in four-wheel drive ; or the hub can disengage -LRB- unlock -RRB- from the axle when four-wheel drive is not needed , thus allowing the front wheels to rotate freely within the hub .. four-wheel drive. four-wheel drive. The hub is a component where the wheel is directly mounted to , and is outside the axle .. Benefits of unlocking hubs for normal road use are mainly found in keeping the front-differential free form unnecessary wear , however , other benefits may include fuel efficiency , quieter operation , less vibration , and lower wear in other driveline components ; however , exactly how great these other benefits are is open to minor debate , with some feeling that they are outweighed by the disadvantages below -. fuel efficiency. fuel efficiency. In some vehicles , manual locking hubs are used to engage the front wheels .. This requires getting in / out of the vehicle to engage or disengage the front wheels .. This may have to be done repeatedly if road conditions are irregular -LRB- shift from snow , then dry pavement , then snow again , repeatedly -RRB- .. In some other vehicles , automatic locking hubs are used which , as the name implies , engage automatically when 4WD is desired .. The main advantage is that the driver does not need to leave the vehicle to activate 4WD , or drive the vehicle in 2WD with the front axle disengaged .. The disadvantage with this system is that most designs require the vehicle to move some distance -LRB- usually a whole wheel turn , often going backwards -RRB- after engaging 4WD , in order for the hubs to engage or disengage -LRB- in many cases , 4WD can be engaged with the vehicle moving -RRB- .. This might not be possible if the vehicle gets completely stuck before 4WD has been engaged , meaning automatic hubs require more caution on the driver 's part .. Exposed hub locks can be broken or damaged by off-road conditions , rendering 4 × 4 useless and leaving the vehicle stranded .. Also , in some axle designs -LRB- such as those used on older Land Rovers -RRB- , the top swivel bearing can become starved for lubrication -LRB- which is normally supplied by oil slung up by the rotating axle -RRB- , unless the hubs are locked every few hundred miles .. Also , since locking hubs generally do not require a key to operate , they can be maliciously locked or unlocked by persons other than the vehicle owner .
not_related.