3 Mixed seromucous salivary glands, structure of glandular acini The three large glands have a different composition in the type of secretory units is concerned: - The parotid glands (which represent 25% of the production of saliva) are formed by serous production units and they are compound acinar type.
How Anti-Lock Brakes Work. An anti-lock brake system (ABS) is a braking system that is made to allow a vehicle to maintain traction with the road when braking. Braking is controlled by driver input via the brake pedal, and older braking systems response to a driver braking suddenly or with intense pressure was sometimes to lock up or skid.
Federal Motor Vehicle Safety Standard No. 121 mandates antilock braking systems (ABS) on all new air-braked vehicles with a GVWR of 10,000 pounds or greater. ABS is required on tractors manufactured on or after March 1, 1997, and air-braked semi-trailers and single-unit trucks manufactured on or after March 1, 1998. Crash data from NHTSA's State Data System and Fatality Analysis Reporting System are used to determine the effectiveness of antilock brakes in heavy tractor-trailer combination vehicles.