Novel braking system, assemblies, and methods for storage and retrieval vehicles finding particular application on dual mast storage and retrieval vehicles where it is important to brake both sides of a carriage disposed between the two masts simultaneously. The braking system comprises an actuator assembly which further comprises a tach/generator which derives rotational energy from the rate-of-travel of the carriage relative to an associated guide rail. An electrical circuit, which runs off power derived from the tach/generator, detects overspeed rate-of-travel of the carriage and sends an electrical signal, also deriving power from the tach/generator, to electrically actuate at least one brake. Each brake is firmly affixed to the carriage and comprises a cam which is electrically driven by a solenoid, to engage an associated guide rail when actuated. When the cam is actuated and the carriage falls toward the braking cam, interposed shock absorbers decelerate the carriage. The brake comprises a lower housing assembly which provides support for the cam and shock absorbers and an upper housing assembly against which the shock absorbers act to decelerate the carriage. An intermediate assembly suspends the lower housing assembly from the upper housing assembly, providing a rhomboid attachment whereby the shock absorbers are maintained in a substantially perpendicular disposition relative to the upper housing assembly independent of the offset of the lower housing assembly from the upper housing assembly.