Caterpillar CT660S: A Comprehensive Overview of the Vocational Truck

[MikePhua]

Introduction
The Caterpillar CT660S is a Class 8 vocational truck that marked Caterpillar's foray into the on-highway trucking industry. Introduced in 2011, the CT660S was designed to meet the demanding requirements of various industries, including construction, mining, and heavy haulage. Despite its robust design and Caterpillar's reputation for durability, the CT660S faced several challenges that influenced its production and reception in the market.
Engine and Performance
The CT660S was equipped with the Cat CT13 engine, a 12.4-liter, inline 6-cylinder diesel engine. This engine was offered in multiple power ratings:

• 365 hp / 1,250 lb-ft torque
  
• 410 hp / 1,450 lb-ft torque
  
• 430 hp / 1,550 lb-ft torque
  
• 475 hp / 1,700 lb-ft torque
  

These engines featured advanced technologies such as dual-series turbocharging, intercooling, and aftercooling, aiming to provide optimal performance and fuel efficiency. The CT13 engine was designed to meet stringent emission standards without the need for Selective Catalytic Reduction (SCR) or Diesel Exhaust Fluid (DEF), relying instead on advanced Exhaust Gas Recirculation (EGR) systems.
Transmission and Drivetrain
The CT660S utilized the Caterpillar CX31 automatic transmission, which offered:

• 6 forward gears and 1 reverse gear
  
• Maximum gross input power of 550 hp
  
• Maximum gross input torque of 1,700 lb-ft
  

This transmission was coupled with a cast aluminum torque converter featuring a lock-up clutch and electro-hydraulic, fully modulated, oil-cooled multidisc clutches. The drivetrain was designed to provide smooth shifting and durability under heavy-duty conditions.
Chassis and Suspension
The CT660S featured a durable chassis with heat-treated alloy steel frame rails, available in 116-inch and 122-inch bumper-to-back-of-cab (BBC) configurations. The frame rails had a yield strength of 110,000 and 120,000 psi, respectively, ensuring strength and rigidity for heavy-duty applications.
The truck's suspension system included:

• Front: Multileaf, shackle-type, single or two-stage spring; multileaf, slipper-type with compatible shock absorbers
  
• Rear: Hendrickson suspension offerings such as HaulMaax, HN, RT/RTE, RS, R, and PriMaax; Chalmers high articulation
  

These suspension options were designed to provide stability and comfort, even under challenging road conditions.
Cab and Operator Comfort
The CT660S cab was constructed using aluminum alloy to reduce overall weight, thereby maximizing payload capacity. The cab design emphasized driver comfort and safety, featuring ergonomic controls and reduced vibration and noise levels. The sloped hood design improved visibility and decreased wind drag, contributing to better fuel efficiency.
Market Reception and Challenges
Despite its promising specifications, the CT660S faced several challenges in the market. One of the primary concerns was related to its engine and emission systems. Many operators reported issues with the emission systems, leading to increased maintenance costs and downtime. Some users even considered engine "deletes" to bypass emission controls, a practice that can lead to legal and environmental concerns.
Additionally, the CT660S's production was limited, and by March 2016, Caterpillar announced the cessation of production for on-highway vocational trucks, citing insufficient market opportunity to justify further investment.
Real-World Experiences
Operators' experiences with the CT660S varied. Some reported satisfactory performance, especially when the trucks were used for lighter duties or in regions with supportive dealer networks. For instance, a company in Michigan reported that their CT660S trucks had approximately 200,000 miles and 10,000 hours of operation, primarily used for heavy-haul tanker work, and had been "decent so far."
Conversely, other operators faced significant challenges. A Reddit user, identifying as an ex-Caterpillar mechanic, advised against purchasing the CT660S, stating, "CT660 is a big reason I left Cat." Another user mentioned that "all the guys I know here in Michigan who bought them to haul heavy ended up getting rid of them in short order due to all sorts of issues."
Conclusion
The Caterpillar CT660S represents an ambitious attempt by Caterpillar to enter the on-highway vocational truck market. While it offered advanced features and the durability associated with the Caterpillar brand, real-world experiences highlighted several challenges, particularly concerning its engine and emission systems. Operators considering the CT660S should weigh these factors carefully and consider the availability of parts and service support in their region.
Key Specifications Summary

• Engine: Cat CT13, 12.4L, 6-cylinder diesel
  
• Power Ratings: 365 hp to 475 hp
  
• Torque: 1,250 lb-ft to 1,700 lb-ft
  
• Transmission: Caterpillar CX31 automatic, 6+1 gears
  
• Suspension: Front: Multileaf; Rear: Hendrickson or Chalmers
  
• Cab Construction: Aluminum alloy
  
• Frame: Heat-treated alloy steel, 110,000 to 120,000 psi yield strength
  
• Emission System: Advanced EGR (no SCR or DEF)
  

Considerations for Potential Buyers

• Maintenance Costs: Be prepared for potential higher maintenance costs, especially related to the emission system.
  
• Parts Availability: Ensure access to parts and service support, as some dealers may be less familiar with the CT660S.
  
• Usage Type: The CT660S may be more suitable for lighter duties or applications where its limitations are less impactful.
  

In summary, while the Caterpillar CT660S offers a robust platform with advanced features, prospective buyers should conduct thorough research and consider their specific operational needs before making a purchase decision.