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Restoring the CAT Twenty-Two and the Hunt for Original Service Manuals
#1
The CAT Twenty-Two and Its Historical Significance
The Caterpillar Twenty-Two crawler tractor was introduced in the mid-1930s as part of Caterpillar’s early push into agricultural and light industrial markets. Built during a time of mechanical innovation and economic recovery, the Twenty-Two was designed to offer reliable traction, simple maintenance, and rugged performance for farmers and contractors alike. With an approximate drawbar horsepower of 22 and a weight of around 6,000 pounds, it filled a niche between the smaller Ten and larger Thirty models.
Caterpillar, founded in 1925, had already established itself as a leader in track-type tractors. The Twenty-Two was manufactured at the San Leandro plant in California and sold primarily in North America, though some units found their way to Australia and South America. Its popularity stemmed from its straightforward design, mechanical durability, and adaptability to a wide range of implements.
Mechanical Configuration and Operating Features
The CAT Twenty-Two was powered by a four-cylinder gasoline engine with a horizontal layout. Key mechanical features included:
  • Bore and stroke: 4.25 x 5.5 inches
  • Displacement: ~312 cubic inches
  • Cooling: Thermosiphon system with radiator shutters
  • Ignition: Magneto-driven with hand crank start
  • Transmission: 3-speed forward, 1 reverse
  • Final drives: Spur gear reduction with dry clutches
The crawler used a manually operated clutch and brake steering system, with levers positioned on either side of the operator. The undercarriage featured riveted track frames, cast idlers, and steel track shoes with replaceable pins and bushings.
In one restoration case from Saskatchewan, a retired farmer rebuilt a Twenty-Two that had sat idle for over 40 years. After replacing the magneto, fabricating new radiator shutters, and re-lining the clutch discs, the machine started on the third crank and was used to pull a vintage harrow across a demonstration field.
The Challenge of Finding Original Service Manuals
Locating service manuals for the CAT Twenty-Two presents a unique challenge. Unlike modern equipment, documentation from the 1930s was printed in limited runs and distributed regionally. Many original manuals were lost, damaged, or discarded over the decades. The surviving copies are often held by collectors, historical societies, or tucked away in private libraries.
Common obstacles include:
  • Manuals printed under the Holt or Caterpillar Tractor Co. branding
  • Variations in part numbers and terminology across production years
  • Lack of digital archives for pre-war equipment
  • Confusion between operator’s guides and full service manuals
  • Fragmented diagrams or missing lubrication charts
In one example from Oregon, a restorer found a partial manual inside a barn wall during demolition. The pages were water-stained but legible enough to identify governor adjustment specs and valve lash settings.
Recommended Sources and Research Strategies
To locate authentic or reproduction manuals:
  • Contact antique tractor clubs and Caterpillar heritage groups
  • Search university agricultural archives and state libraries
  • Explore estate sales and farm auctions for vintage literature
  • Reach out to retired CAT dealers or mechanics with long tenure
  • Use serial number prefixes to narrow down production year and variant
Serial number prefixes for the Twenty-Two typically begin with 2F or 3J, depending on configuration. Matching the prefix to the manual ensures correct specifications for engine timing, clutch adjustment, and track tension.
In Australia, a collector sourced a complete manual set from a retired dealer who had kept binders from the 1940s. The manuals included exploded diagrams, lubrication schedules, and troubleshooting flowcharts—critical for rebuilding the magneto and governor linkage.
Restoration Tips and Practical Advice
When restoring a CAT Twenty-Two without a manual:
  • Use micrometer measurements to verify bearing clearances
  • Reference similar models like the CAT Twenty or Thirty for baseline specs
  • Photograph each disassembly step for reassembly guidance
  • Mark gear teeth and linkage positions before removal
  • Use period-correct lubricants such as SAE 30 non-detergent oil
  • Fabricate gaskets using fiber sheet and hole punches if originals are unavailable
In Maine, a restorer rebuilt the steering clutch using leather pads soaked in linseed oil—a method documented in a 1937 dealer bulletin. The clutch engaged smoothly and held torque under load, proving the value of historical techniques.
Operator Stories and Field Wisdom
In California, a Twenty-Two was used to pull a hay rake across a demonstration field during a vintage equipment show. The operator noted that the machine ran cooler after installing a new fan belt and cleaning the radiator core with compressed air.
In Manitoba, a collector used his Twenty-Two to grade a gravel driveway. After adjusting the carburetor float and replacing the spark plugs with modern equivalents, the engine ran steadily and consumed less fuel than expected.
Conclusion
Restoring and maintaining a CAT Twenty-Two is a journey into mechanical history. While service manuals may be elusive, the machine’s design invites hands-on learning and community collaboration. With patience, resourcefulness, and respect for original engineering, these early tractors can return to life—reminding us that even in the age of electronics, steel and simplicity still have a place in the field.
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