Peterbilt 335/337 Service Truck

The Peterbilt 335 and 337 series represent a class of medium‑duty vocational trucks widely used as service, mechanic, and utility trucks in construction, field maintenance, and industrial applications. Built by Peterbilt Motors Company, a respected U.S. truck manufacturer with roots stretching back to the 1930s, these models offer a blend of durability, torque capacity, and customization potential that make them ideal platforms for crane‑equipped service bodies, tool storage, and on‑site repairs. The 337 replaced the 335 as Peterbilt’s mid‑range model, with improvements in visibility, cab design, and powertrain flexibility. Professionals seeking a service truck chassis often pair these trucks with aftermarket service beds and cranes to create mobile workshops capable of handling heavy‑duty tasks in remote and urban environments alike.

Peterbilt Brand and Model Lineage

Peterbilt is a long‑established truck manufacturer known for rugged, vocationally focused vehicles. In the late 2000s and early 2010s, the company revised its medium‑duty lineup: the Model 335 was phased out and succeeded by the Model 337 as a more modern, efficient, and versatile chassis for vocational use. The 337 occupies Class 6–7 weight categories, with Gross Vehicle Weight Ratings (GVWRs) typically between 26,000 lb and 33,000 lb, making it a mid‑range choice between light‑duty pickups and heavy‑duty Class 8 tractors.

Purpose and Applications of Service Trucks

Service trucks—also called mechanic trucks or utility trucks—are specialized vehicles designed to support field service, repairs, maintenance, and equipment transport. They are essential for industries where equipment failure or breakdowns must be addressed without returning to a central shop, such as remote construction sites, utility corridors, mining operations, or agricultural estates. Common service truck functions include:

• Performing on‑site mechanical repairs to machinery and equipment
• Supporting welding and fabrication tasks with built‑in power systems
• Carrying specialized tools and spare parts
• Providing crane assistance for lifting heavy components
• Supplying air compressors or generators for auxiliary power

Service trucks save time and reduce downtime by bringing the shop to the job, which can be critical in industries that cannot afford extended equipment outages.

Key Features of the 335 and 337 Chassis

Both the 335 and 337 are designed with attributes that suit service truck applications:

• Medium‑Duty GVWR: Suitable for service bodies and cranes without needing a full Class 8 chassis
• Cab Design: Aluminum or lightweight cab options improve fuel economy and corrosion resistance while maintaining strength
• Engine Options: PACCAR PX‑series engines (PX‑6, PX‑7, PX‑9) delivering between roughly 200 and 380 hp and robust torque for accessory loads and crane operations
• Suspension Choices: Spring or air‑ride suspensions that balance ride quality with load‑carrying capability
• Transmission Options: Manual and automatic choices from Eaton Fuller and Allison systems to match driver preference and duty cycle
• Ergonomics: Driver‑friendly dashboards, good visibility, and multiplex electrical systems for diagnostics and ease of maintenance

These chassis form the basis for service trucks that technicians build out with service bodies, storage compartments, and heavy‑duty cranes.

Service Body and Crane Upfit

When configuring a 335/337 service truck, popular upfit elements include:

• Service/Mechanic Bed (typically 14 ft) — Provides organized storage for tools, spare parts, hose reels, and safety equipment
• Cranes (e.g., 10,000–12,000 lb capacity) — Mounted forward of the bed to lift engines, pumps, and heavy components
• Hydraulic Outriggers — Stabilize the truck during crane operation, enhancing safety and load handling
• Air Compressors & Generators — On‑board systems that power pneumatic tools and electrical equipment without a separate power source

These features transform a basic truck chassis into a mobile workshop capable of performing heavy lifting and complex tasks onsite. Capacity and configuration depend on the body manufacturer and intended use, but a typical mechanic service truck will integrate a crane rated in the 10,000–12,000 lb class with compartments sized for wrenches, welding torches, and diagnostic tools.

Terminology Explained

To understand service truck discussions and specifications, it helps to know key terms:

• GVWR (Gross Vehicle Weight Rating): The maximum total weight of the truck, passengers, cargo, and upfit equipment that the vehicle is designed to carry safely.
• PACCAR Engine: A family of diesel engines produced by PACCAR that balance power with efficiency; often used in Peterbilt trucks.
• Multiplex Electrical System: A wiring architecture that uses fewer wires and centralized control modules to reduce weight and simplify diagnostics.
• Outriggers: Extendable supports that stabilize a truck during crane lifts to prevent tipping.
• Service Bed: The custom body mounted behind the cab that houses tools, cables, and auxiliary equipment.

Understanding these terms helps buyers evaluate capabilities and match them to their work needs.

Real‑World Considerations When Buying

When shopping for a service truck based on a 335 or 337 chassis, buyers often consider:

• Cab and Frame Condition: Rust‑free frames and intact cabs improve longevity and resale value.
• Engine Hours and Maintenance History: Lower hours and documented service often predict greater reliability.
• Crane and Outrigger Condition: Hydraulic crane systems should be inspected for leaks, proper lift capacity, and safe control operation.
• Upfit Quality: Welding, compartment design, and tool storage layout can significantly affect daily productivity.
• Mileage vs. Hours: In service trucks, engine hours often reflect equipment usage better than miles, as many jobs involve idle time while performing repairs.

Tools such as TruckPaper, auction listings, and dealership inventories help buyers track pricing and availability across the used market, with service truck prices ranging widely based on age, condition, and configuration.

Case Stories and Industry Insight

Experienced fleet managers often share anecdotes illustrating how a well‑configured service truck saves time and money: one contractor recounted replacing an excavator hydraulic pump on site using a Peterbilt service truck equipped with a 10,500 lb crane and air compressor. What otherwise would have required towing to a shop was completed in hours, enabling the crew to return to productive work the same day. Another operator emphasized inspecting outriggers and crane safety features thoroughly before purchase, noting that overlooked wear in hydraulic seals can lead to costly field repairs.

In municipal and utility use, service trucks based on 337 chassis have become common for tasks ranging from water‑main repairs to streetlight maintenance, where onboard cranes and compressors streamline operations without requiring separate equipment. These real‑world deployments highlight the value of a truck that combines mobility, power, and on‑the‑spot capability.

Safety and Best Practices

Operating a service truck with a crane and heavy tools involves inherent risks, so safety protocols are essential:

• Stabilize Before Lifting: Always deploy outriggers and confirm ground stability before operating a crane.
• Load Ratings: Understand and respect crane load charts to avoid overstressing the boom.
• Inspection Routines: Daily checks of hydraulic hoses, crane pins, and leveling systems reduce the risk of failure during use.
• Training: Operators should be trained and certified when required by local safety standards, especially for crane operation.

These best practices reduce on‑site accidents and protect both personnel and equipment.

Conclusion

The Peterbilt 335 and 337 service truck platforms offer versatile, reliable foundations for demanding field service applications. With rugged cab design, strong engine options, and the ability to integrate service bodies, cranes, compressors, and more, these trucks bridge the gap between transportation and mobile workshop needs. Buyers considering these chassis should weigh cab/frame condition, upfit quality, and maintenance history to ensure long‑term operational success. When configured and maintained properly, a 335/337 service truck becomes an indispensable tool for contractors, utility providers, and equipment technicians alike, delivering power and capability wherever the work takes them.