Mid-'60s Ford manual steering...
Mid-'60s Ford manual steering uses Saginaw's recirculating ball-and-nut engineering. Ford trucks relied on Gemmer worm-and-roller steering from 1937-60. The transition to ball-and-nut steering was an improvement in efficiency and dramatically increased the longevity of manual steering gears.
Manual steering gears predate the Model T era. The typical layout is a column and shaft leading from the steering wheel to a frame-mounted gear mechanism. This steering shaft rotates left and right, turning a cross-shaft within the gear. The cross-shaft rotates the pitman arm, and depending upon the front axle layout, the pitman arm moves either fore-and-aft or laterally.
The manual gear mechanism can be a worm-and-sector, worm-and-roller, cam-and-lever, or recirculating ball-and-nut design. In each type gear, the aim is to: 1) Change the direction of steering input motion by 90 degrees, and 2) Establish a steering ratio between the input shaft and the cross-shaft. Although mechanisms differ, the function remains the same: convert steering wheel input into pitman or steering arm rotation. Linkage connects the pitman arm to the steering arms and knuckles at the front wheels.
Types Of Manual Gears
In concept and basic design, manual steering gearboxes have changed very little in the past century. Prior to 1972, several American manufacturers produced manual steering gears. Despite similar outward features, these gears have different internal mechanisms. Let's discuss these components and steering gear terminology.
A 1925 patented Ross single...
A 1925 patented Ross single pin (cog) cam-and-lever steering was popular on Dodge, Graham-Paige, Reo, and Mack trucks. Ross built cam-and-lever steering gears as late as 1971. In their best form, the heavy-duty truck versions of these gears had twin studs that rotated on double-tapered roller bearings. I-H, Studebaker, and others used Ross gears.
The worm/worm shaft/worm gear can be a spiral, screw-like gear or a spiral groove machined into the steering shaft. Some worms engage directly with the sector or roller teeth. On recirculating ball-and-nut gears, the worm is a machined, spiral groove in the steering shaft. The groove serves as a ball bearing race. In a cam-and-lever gear, the worm is a cam designed to move the pins of a lever shaft. When the steering wheel turns left or right, the worm or cam rotates clockwise or counterclockwise.
The sector, pitman shaft, cross-shaft, or lever shaft rotates the pitman arm. Though subtly different by design, each of these shaft types lay perpendicular to the centerline of the input or worm shaft. Supported by bearings or bushings, the shaft has splines and a nut at its outer end. The pitman arm attaches to these splines. Movement of the worm shaft rotates the sector/cross-shaft.
Various patents apply to manual steering gear designs. Manual steering gear terminology frequently associates a design with its manufacturer. These terms and names can be useful when describing or ordering parts for a manual steering gear.
This Ross twin-pin lever shaft...
This Ross twin-pin lever shaft is common to vintage Jeep trucks, I-H Scouts, and Studebaker. Pins do not rotate. Over time, these pins develop a pair of flats at opposite sides of each cone. Compensating with an adjustment is risky and simply borrows time. This gear needs a new lever shaft and bushings.
Ross cam-and-lever steering uses a steering column tube or input shaft with a cam at the bottom. This worm cam resembles round bar stock with a spiral groove machined into the cam. A lever is at the inner end of the lever shaft. Pins on the lever engage the cam groove. At the outer end of the lever shaft, splines attach to the pitman arm. The lever pins move with the steering wheel and cam rotation, swinging the lever shaft and pitman arm clockwise or counterclockwise.
Ross cam-and-lever gears are common to Jeep, International-Harvester, and Studebaker trucks. The heyday of Ross gears was the pre-war period to mid-'60s. Primitive and wear-prone, light-duty Ross cam-and-lever gears have fixed lever pins and a higher friction factor than other designs. Heavier-duty Ross gears mount the lever pins on bearings. Those designs are available in both single- and twin-stud versions.
Gemmer worm-and-roller gears were popularized in '37-up Ford cars and truck models. The predecessor of the worm-and-roller was Gemmer's worm-and-sector gear. Vintage Dodge pickups also use this gear type. The roller rides on needle bearings and mounts on a shaft at the head of the sector. This rotating roller engages the worm. Friction is much less than with a worm and fixed-tooth sector; a fixed tooth design is sliding friction. The roller is a much smoother rolling friction.
 Two-tooth roller and worm...  Two-tooth roller and worm is a Gemmer type. You will find this worm-and-roller design on '37-52 Ford trucks, Ford passenger cars, and Dodge trucks. Gemmer was a major supplier of worm-and-roller steering gears. G.M. and Ross had their own versions of the design. The roller is an improvement over earlier worm-and-sector gears. |  This is a new worm and bearings...  This is a new worm and bearings for the Gemmer gear. Suppliers now offer the worm and shaft as a unit, a wise way to purchase these parts. Otherwise, special tooling is necessary for pressing the worm off and on the column tube. The force needed is considerable; the tube must be supported in a sleeve to prevent bending. |  A new sector roller matches...  A new sector roller matches the new worm. Note the shape of the spiral worm. The curvature at each end maintains tooth contact as the roller moves left and right. That movement rotates the sector shaft, which attaches to the pitman arm by way of splined teeth and a large nut with lock washer. |