<div class="section abstract"><div class="htmlview paragraph">THE LABORATORY has been described as an “indoor” proving ground. However, laboratory investigations are not intended to substitute for proving ground activities, but rather are a necessary counterpart. Interrelation between the two becomes more clear when considering some of the laboratory's inherent advantages:</div><div class="htmlview paragraph"> <ol class="list nostyle"> <li class="list-item"> <span class="li-label">1.</span> <div class="htmlview paragraph">It permits close investigation of the operation of inaccessible parts.</div></li> <li class="list-item"> <span class="li-label">2.</span> <div class="htmlview paragraph">Small differences in design performance may be evaluated through precise control and measurement of test conditions.</div></li> <li class="list-item"> <span class="li-label">3.</span> <div class="htmlview paragraph">Road conditions, due to inclement weather, are of no concern.</div></li> <li class="list-item"> <span class="li-label">4.</span> <div class="htmlview paragraph">The delay of transmission tests due to failure of other vehicle components is eliminated.</div></li> <li class="list-item"> <span class="li-label">5.</span> <div class="htmlview paragraph">By utilizing automatic shut down features, it allows close inspection and pin-pointing of source of failure.</div></li> <li class="list-item"> <span class="li-label">6.</span> <div class="htmlview paragraph">It allows accelerated testing since measured proving grounds data may be adjusted a given percentage before being put into a fixture.</div></li></ol></div><div class="htmlview paragraph">This paper describes the laboratory testing of automatic transmissions.</div></div>