How Variable Rudder Control Was Installed in Slo-Mo-Shun [1950]

Slo-mo-shun IV Steering Gear
Slo-mo-shun IV Steering Gear

Ted Jones, designer, and Anchor Jensen, builder of Seattle Chrysler dealer Stanley S. Sayres' Slo-Mo-Shun IV, solved one requirement — that of variable rudder control — in a simple fashion, working with Western Gear Works.

The design had to provide for:

The solution worked out was to use a standard Michigan Tool Company Cone-Drive double enveloping gear speed reducer mounted outboard at the stern. As shown in the accompanying sketch the pinion in the reducer is linked to the steering column through a 10-foot long tubular shaft drive with two universal joints and a set of one-to-one ratio bevel gears, while the gear shaft is inserted directly into one of the splined rudder posts.

With this design, it was possible to:

With this setup, a 10-to-1 ratio gear set was used in the Cone-Drive reducer to control the rudder while the boat was setting the world's record of 160.3 mph.

For the Gold Cup race, a 5-to-1 reduction gear set was used, the speed reducer gears being simply interchanged to provide the different ratio.

Included in the steering setups used with this drive to date on the Slo-Mo-Shun IV are:

(Reprinted from Pacific Motor Boat, November 1950, p.45)