The Model T Crank Ratchet and
How It Changed
This article arises from a casual encounter with another Model T enthusiast. Some time ago we were following one of my favorite past times-pawing through someone else's collection of spare Model T parts when this friend handed me a Model T crank ratchet and asked if I had ever seen anything quite like it. It appeared to be made out of pressed steel, and no I hadnít seen one before. But I volunteered to look it up on my next trip to the Research Center at the Henry Ford Museum and Greenfield Village in order to establish whether or not Ford ever produced such a part.
What I thought would be a simple ten-minute research topic became a very extensive project when I learned that there were seven distinguishably different crank ratchets used during the Model T's nineteen year production run. The project also became an obsession as I searched for examples of the six ratchet styles used on the production 1909 and later Model Ts.
|Figure 1. These are the parts used on the first 2500 Model Ts. The drawings at the left are T-528A (left)and T-527A (right). T-528A is the part that fits the crank. T-527A fits the crankshaft of the engine. The photo on the right shows these installed on the car.|
The first design crank ratchet was used on only the first 2500 Model Ts. This style is really very different from the six that followed it. It was, in fact, a two piece affair. Both parts were drop forgings. One piece slipped over the end of the crankshaft and the other over the end of the starting crank. Teeth were cut in both parts that were designed to fit together when the crank was engaged. The part which attached to the starting crank was given the factory part number T-528 (see Figure 1 ).
When the Model T engine was redesigned in late 1908 (for cars after #2500), the starting crank ratchet was redesigned as well. The new crank ratchet set the pattern for all the ratchets to follow. It was designed to eliminate the T-527-A mating ratchet used on the end of the crankshaft of the earlier cars. The new design was designed with teeth to engage a 3/8-inch diameter straight pin that was driven into the front of the crankshaft. This pin served the dual purpose of holding the new fan belt pulley on the front of the crankshaft as well as serving as the engagement point for the ratchet. This crankshaft ratchet design was adopted on December 23, 1908 and was given the factory part number T-528-B to distinguish it from its predecessor.1
The earliest one-piece design of crank ratchet is easily recognizable from the later ratchets because they are made from drop forgings. Most will have the factory number and trademark of the manufacturer embossed on the front side of the ratchet. Two variations of this ratchet have been observed.
The most common version has bosses forged into the ratchet at the hole for the ratchet attachment pin (see Figures 2 & 3). The other version is virtually identical to the other except that these bosses have been eliminated (see Figure 4). Unfortunately the Ford Engineering records do not reveal when the bosses were eliminated nor the reason for the change.
|Figures 2 and 3. This is the ratchet used after the first
2500 until October 1912.|
Figure 4 on the right was used at the same time but does not have the bosses around the rivet hole
In September 1912 the crank ratchet was completely redesigned and the third type of ratchet appeared. While this third type still used the factory number T-528-B, the material was changed from a drop forging to pressed steel. The new design also changed several of the dimensions of the ratchet. The pocket for the crankshaft was made 1/16-inch deeper while the length of the small end was reduced 1/16 inch, thus leaving the overall dimensions the same. These ratchets are clearly identifiable by the lack of any part numbers or manufacturerís trade-mark. On examples in good condition the draw marks left from the stamping dies can be clearly seen on the small diameter of the ratchet 2 (see Figures 5 and 6).
Figure 5. The third design ratchet, now made of pressed steel, used from late 1912 to about August 1913.
Figure 6. Another third design of the pressed-steel ratchet. This one differs in shape from that in Figure 5, and was removed from a May 1913 car. The difference in the shape is not explained in the engineering records but may be due to differing suppliers.
Figure 7. The fourth design, also made of pressed steel.
Figure 8. The third (left) and fourth (right) designs shown for comparison. Note the difference in the notches in these two types.
The fourth design appeared in August 1913 and it is also a pressed steel ratchet. The new style pressed ratchet can be distinguished from the earlier pressed steel style by the notches for the crankshaft pin. The points of the teeth of the new style were much more rounded than on the old design (see Figures 7 and 8). If two of the new style ratchets are fitted together the teeth form perfect mates. When Joseph Galamb of the Ford Motor Companyís Engineering Department notified the Globe Stamping Co. of Cleveland, Ohio of the new design, he provided them with a sample ratchet showing the desired shape of the notches. He also noted that his sketch for the new design "does not show the correct shape of the notches when in the blank before being drawn, which shape will have to be determined by cutting and trying."3
Figure 9. The fifth design was a malleable iron casting. This type was used from about May 1914 through August 1918.
Figure 10. The crank ratchets used after May 1915 have a part number T-528 and the manufacturer's trade mark cast into the pocket of the ratchet.
Figure 11. The fourth and fifth designs side by side. The sixth design pockets are 1/8-inch shorter than those on the fifth type. The sixth type was used from about August 1916 to August 1920.
On April 28, 1914 the crank ratchet was completely redesigned again. In this fifth design of starting crank ratchet the material was changed from a pressed steel stamping to malleable iron. All the contracts for pressed steel for making the old design were canceled and orders were placed for metal patterns for the new design. Joseph Galamb must have had some misgivings about the new design because he wrote "Would suggest, however, that the dies which have been used for making this ratchet out of pressed steel be kept for a while."4
The fifth design was dimensionally identical to the design it replaced. The earliest examples are unmarked. They are about 2-5/32-inches long with notches of the same design as found on the later pressed steel ratchets (see Figure 9). Beginning in May 1915 the factory number and foundry trademark were added to the inside of the ratchet at the bottom. The letters are sunk into the casting (see Figure 10).
In August 1916 the Ford engineers reduced the overall length of the malleable iron crank ratchets. On this sixth design of crank ratchet the depth of the crank pocket was reduced from about 15/16-inch to 13/16-inch. This made the new ratchets about 1/8-inch shorter than the fifth design (see Figure 11). Fitting the teeth together of the old and new designs shows the difference between them. The teeth on the sixth style will not extend all the way down to the bottom of the crank pin pockets on the fifth style.5
Figure 13. Note the "Ford" in block letters. This was used beginning about April 1918.
Figure 14. The "Ford" was changed to script about March 1919.
Figure 15. The seventh design, adopted in August 1920 and continued until the end of Model T production.
Figure 18. The sixth and seventh types shown for comparison. The shank that fits over the crank on the seventh type is 1/8-inch shorter than that of the sixth type.
In April 1918 the name Ford was finally added to the crank ratchet. The letters were in block style and sunk into the casting at the bottom of the crank pocket. Eleven months later on March 19, 1919 the block-letter name Ford was replaced with Ford script (see Figures 13 and 14).6
The seventh and final crank ratchet design was adopted in August 1920. The Ford Engineers reduced the over all length of the ratchet a second time. The distance from the center of the crank ratchet pin hole to the rear end of the ratchet was changed from 5/8-inch to 1/2-inch and the overall length was reduced to 1-29/32-inches. This is the shortest and the most common of all Model T ratchets (see Figures 15 and 16). Many variations of the seventh style crank-shaft ratchet have been observed. While all of them are of the same size and shape, they vary extensively in terms of the type and location of their markings. In fact, it is hard to find any two crank ratchets that are completely identical!7
While on the subject of the starting crank ratchet, now might be a good time to bring up the subject of the pin used to attach the ratchet to the starting crank. When the forged design crank ratchet was adopted in late 1908, the Starting Crank Ratchet Pin, factory part number T-527-B was adopted at the same time. This was a straight steel pin 5/16-inch in diameter and 1-3/8-inch long. The ratchet was attached to the crank by riveting over both ends of this pin, making the ratchet more or less a permanent part of the starting crank (see Figure 17).
Figure 17. This photo is from an original 1917 Ford. Note that the ratchet is riveted to the crank, not held with a rivet and a cotter pin.
When the pressed steel crank ratchet was adopted in 1912, a new pin was designed and given the factory part number T-4491. This too is a straight steel pin 5/16-inch in diameter, but it is only 1-3/16-inch long because the stamped steel ratchets were smaller in diameter at the pin hole than the forged ratchets were. These pins were also riveted over on both ends, again permanently attaching the ratchet to the starting crank. The adoption of the malleable iron design ratchet in 1914 made it necessary to change the length of the pin again, this time increasing it to 1-1/4-inches long. Despite being longer, it was considered to be useable on both the pressed steel and malleable iron ratchets.
The Ford Motor Company was always seeking ways to cut costs, and on September 21, 1914 C. Harold Wills changed the material specification for this pin from open hearth steel to scrap valve stem stock. Waste not, want not was the rule at Ford.8
Finally on March 28, 1919 Joseph Galamb made the lives of most Model T mechanics much more pleasant by changing the design of the pin from a straight pin to a rivet with a cotter pin hole. According to Galamb "This change was made to eliminate riveting the pin in place, which is causing a lot of leaks at present, and is to take effect at once: pins on hand to be scrapped if they cannot be used in other ways." This design continued until the end of Model T production in 1927.9
This has been a rather exhaustive article about an obscure part. Under the best of circumstances crank ratchets are difficult to see when installed on a Model T. Even then the markings which identify the era when a particular ratchet was made, usually cannot be seen because of their location inside of the crank pocket. Owners of pre-March 1919 Model Ts will probably not be thrilled to learn that the crank ratchets on their cars were riveted on instead of using the much more convenient rivet and cotter pin. So why bother?
The answer to this comes in several parts. First of all, by making this extensive study of the crank ratchet we have seen how the Record of Changes or Releases, as they are sometimes called, can be used to date changes in the design of a typical Model T part. Furthermore, parts of unusual shape or design (e.g. the pressed steel crank ratchet) can often times be documented as a genuine Ford design from this source.
Often times the Releases will tell us about part designs that we hadnít recognized as ever being used. For example, while searching for samples of each of the different crank ratchets to use with this article I realized from a careful reading of the Releases that an intermediate length malleable iron (sixth style) ratchet was used from late 1916 until mid-1920. So I went back to scrounging through the ratchet collections of my friends until I turned one up.
This article also shows how helpful the Releases can be in providing background information on the changes in the designs of Model T parts. The comments that Joseph Galamb made about cutting and trying the shape of the notches of the pressed steel ratchet, or about changing the starting crank pin in order to eliminate the oil leaks caused by riveting the pin in place are priceless. They give us new insight into the operation and procedures practiced by the Ford Engineering Design Dept. during the Model T era.
Finally, this study of crank ratchets has illustrated the incredible richness and diversity in the design of Model T parts. Crank ratchets are not an isolated example. A large number of Ford engineering documents have just become available for study during the past two years. As we probe deeper into these documents we are finding that change and experimentation was an ongoing process during the Model T era. Model Ts were not so much alike as peas in a pod, as they were variations around a central theme. The overall design of the Model T may have remained the same, but the parts of which it was built changed frequently over time.