coupled to the hoisting motor 30 through the hoisting motor shaft 32 a shaft encoder 34 is mounted on the other end of the hoisting motor 30 and coupled to its shaft 32 to count the number of turns the shaft 32 makes the information from the shaft encoder is fed back to the load oscillation dampener 14 and is used to compute the instant length of the hoisting rope 16 from which the period of oscillation of the load may be computed fig2 a is a graph of the speed of the carriage 4 vs time which would result if the operator inched the carriage 4 while the load oscillation dampener 14 operates on the aforementioned conventional open loop principle that load oscillation can be damped by applying an acceleration interval followed by an equal acceleration one half period later the operator begins the inching procedure at time t0 by issuing an initial motion command for the carriage 4 in a certain direction the operator issues the initial motion command for example by pressing a pendant button 36 at time t0 the carriage begins to accelerate at a predetermined acceleration rate acc1 to reach the speed v1 which is attained at time t1 the acceleration rate acc1 is indicated by the slope of the graph between times t0 and t1 at time t2 the carriage 4 nears the.