Why Did Kenworth Stop Making Cabover Semi Trucks? (And Which Was The Last One Made?)

Kenworth is probably best known by some people today for its long-nose conventional trucks. But it has had a rich and varied history that also involves cabover trucks. The company's production journey began in 1923 when it was incorporated by Harry Kent and Edgar Worthington. It delivered just 80 trucks in 1924, but by 1930, yearly volume had climbed more than 212% to 250 units. Some six years later, in 1936, Kenworth's portfolio expanded to include the bubble-nose Model 516, its first cabover truck.

The Model 516 cabover truck was created in response to the Motor Carrier Act of 1935, which imposed a limit on the size and weight of trucks and trailers allowed on U.S. roads, with each state given the freedom to determine its own set of restrictions. In New Mexico, for example, the government set the maximum truck length as 45 feet overall and also required truckers to comply with a weight per axle limit. So, in an attempt to adhere to the restrictive length laws, Kenworth jumped from traditional cabs to the cabover body style, which positions the cab over the engine in order to save some length.

Not surprisingly, the following decades brought a wave of cab-over-engine trucks to U.S. roads as the design became popular. However, a rule change in the '80s relaxed the length laws, causing a shift toward the conventional hooded trucks that are now a common sight on U.S. roads. With length no longer an issue, manufacturers began to dial back on cabovers in favor of long-nosed semi-trucks. Kenworth, for one, stopped producing on-the-road cabover semi-trucks for the U.S. market in 2002 after it discontinued the iconic K100 line but kept on building the K500 severe-service off-highway truck until 2020.

By the time it was due to be retired in August 2020, Kenworth's last cabover semi-truck model, the flat face K500, had spent 14 long years on the market, having entered production in 2006 at the company's manufacturing facility in Renton, Washington. A total of 283 K500 severe-service off-highway trucks were made in that time, with the total unit spread across 6×4, 6×6, 8×8, and 10×10 configurations.

All models were shipped abroad to various companies with interests in, among other things, gold mining and oil and gas exploration. The last Kenworth K500 built at the Renton plant was bought by Sintagma Holding and shipped over to Luanda, Angola, for use in a gold-mining operation by the Mining Society of Chitotolo (Sociedade Mineira do Chitotolo).

During its production run, the K500 was built off a Kenworth C500 drivetrain and also had a Cummins engine that developed 525 hp and 1,650 lb-ft of torque, with the powertrain mated to an Allison 4700RDS 7-speed transmission. Following the K500's discontinuation, customers were left with the likes of the Kenworth C500 as options. However, it seems the C500 isn't long for this world either, as Kenworth is set to officially discontinue the model in 2026 along with other 1.9-meter cab Class 8 trucks such as the T800 and W900 due to tightening emissions laws and component constraints.

Helped by its flat face, the cabover was quite a beneficial design that brought with it a high-mounted seating position closer to the windshield, affording drivers plenty of visibility on the road. The shorter wheelbase and overall length meant the cabover truck was also generally easier to navigate through narrow streets than its conventional counterpart. But it also had shortcomings that inconvenienced operators. 

Cabovers weren't easy to get out of, for one thing, and drivers often struggled to get used to the firm ride quality, which they found very uncomfortable on long journeys. The cabin also tended to get warm during a trip because it was in such close proximity to the engine. Then there's the matter of the cabin being quite small and not giving drivers a lot of space, which made some feel confined or claustrophobic. But perhaps the biggest issue with the cabover design relates to safety. Front-end collisions involving cabovers were more likely to cause serious physical injury to occupants, since the design has a flat front end and does not include a hooded extension that can absorb the force of impact in a head-on collision.

In conventional long-nosed trucks, the cabin is located behind the engine, and this makes for a cooler interior overall. Front-engine semi-trucks also have a more comfortable and spacious cabin, not to mention their hooded design means they're more aerodynamic and consequently more fuel-efficient than flat-faced cabovers.