Gray Motor Company
The Gray Gearless has a flexible shaft drive. They advertized it as "the strongest part of the motor", and went on to explain to prospective buyers how tough it was.
They touted the fact there was " no wasted power" from the need for bevel gears, plus Grays didn't have the weight due to "cumbersome speed retarding containing hubs". The gearless drive is "made of Chrome Vanadium, heat treated; maximum strength 250,000 pounds per square inch" and all the power from the motor is delivered smoothly to the propeller "with no chance to wear" because "the vanadium universal drive carries in a spring tube engine grease".
The downside, as mentioned in the owner's guide (not the ads) is that once a month you have to disconnect the shaft and pour heated grease into it!!
|Below is excerpt from a great article in The Rudder on all major makes of 1915. Great photos!!!|