The Peterbilt 320 features a cab over engine configuration and was designed for the refuse and vocational industries. Thanks to its wide range of engines and axle configurations the model is one of the most versatile trucks produced by the American manufacturer. Besides the typical diesel engines, the Peterbilt 320 is also available with a hybrid technology which offers significantly lower fuel consumption without sacrificing the payload capacity. Optional frame liners are also offered for heavier missions, while a power take off system is available for both front mounted and transmission driven configurations.
The Peterbilt 320 is priced around $130.000 and its latest upgrades were made in 2012 when it received new steering gears, a lightweight battery box, ergonomic seats and innovative tri plane mirrors.
The 210, 220 and 320 models are the only cab-over-engine trucks in Peterbilt’s lineup. Thank to this configuration, the 320 is easier to maneuver around the city and also offers more space inside than a conventional cab.
The overall design is pretty rudimentary with a completely flat front dominated by a simple radiator grille traversed by three vertical stripes. The rectangular headlights are also pretty simple and enhance the utilitarian look of the truck. The marker lights feature LED technology which extend service intervals and are also more efficient than the conventional lights.
The huckbolted aluminum cab features lap seam construction and bulkhead style doors. For a higher durability, the sub frame is zinc-coated to be more resistant to corrosion.
The truck was design with the utility in mind and access to the engine is made very easy thanks to the industry-leading 65º cab tilt which offers full access for technicians.
Once inside, you’ll get the same utilitarian look that was found outside. Needless to say, that all the materials and plastics are from the “rock-hard” side, while the fittings could’ve been better.
For enhanced convenience, the dashboard is slightly curved to the left driver, but we find it a bit cluttered and distracting as the layout isn’t quite as intuitive as other trucks in the segment. On the other hand the Peterbilt 320 is available in left-hand, righthand and dual-drive with right-hand stand up configurations which make it one of the most versatile vocational trucks on the market.
The steering wheel however, is a bit too big for our tastes and some may consider it uncomfortable to use. The good part is that is can be adjusted for both reach and rake and also folds out of the way facilitating the driver’s access inside the cab.
In 2012 Peterbilt has upgraded the 320 seats and now offers an armrest, headrest and additional lumbar support to the Sears C-2 air suspension seats. The seats also deliver 5.25 inch suspension travel with ergonomic contoured molded cushions and are fairly comfortable even for the long runs. All the new features are available on both the driver and passenger seats.
Thanks to the high mounted seats, the all round visibility is top notch and we also like that the huge windshield is split in two individual section which, compared to a one piece unit, cost less to be replaced in case of a partial damage.
To further enhance visibility and safety, Peterbilt’s added new tri-plane mirrors on the upper and lower planes with a remote controlled flat mirror on the middle plane. All three surfaces are heated, and feature an arm system that allows the mirror to be folded either forward or backward. Moreover, the mirrors can be either traditionally mounted on the driver and passenger doors, or the passenger side mirror can be installed to the front of the cab offering a better rear visibility.
Engines and transmissions
The Peterbilt 320 is available with Cummins ISLG, ISL9 and ISX 11.9 engines which offer a range of outputs between 310-385 hp.
The Cummins ISL engines are significantly lighter than any other engine in their class, and despite their low weight they don’t sacrifice the power outputs or the towing capabilities.
The Cummins engines also feature a high-pressure fuel system that delivers high injection pressures independent of engine speed for enhanced throttle response, fuel economy and emissions reduction.
The Cummins engine is standard with the Horton Drivemaster fan clutch and a Cummins 18.7 CFM air compressor. Moreover, the units can be also optionally combined with the Jacobs C-brake or an engine protection system.
The engines can be matted on either Fuller manual gearboxes or with Allison auto transmissions with 4, 5 or 6 speeds.
Besides these conventional models there is also a hybrid version of the Peterbilt 320 which is powered by a Hydraulic Launch Assist (HLA) technology to lower the truck’s emissions. The company said that the 320 Hybrid was engineered to meet the reliability demands of refuse collection routes with 800-1200 stops per day.
The hydraulic system captures the truck’s kinetic energy during braking to assist in launching and accelerating the vehicle. The HLA technology works by recovering up to 75 percent of the energy normally lost by the vehicle’s brakes in the form of pressurized hydraulic fluid which is stored until the next acceleration.
There are two modes available for the Hybrid 320 model, namely the “fuel economy” and the “Performance”. In the “fuel economy” mode the stored energy is used to start the truck without using the primary engine, while in the fuel “Performance” mode the stored energy is mixed with the engine power at launch improving the acceleration and keeping the fuel consumption to a low level.
Peterbilt says that the Hybrid Hydraulic Launch Assist System provides up to a 30% improvement in fuel efficiency, up to a 28% reduction in emissions and 3 to 4 times brake life improvement.
ISL G 320
ISL G 300
ISL G 280
ISL G 260
ISL G 250
Ride and suspensions
Usually, a cab over engine configuration offers a good maneuverability, but on the other hand affects the ride comfort as every road bumper is transferred directly into the driver’s spine. However, the air suspended seats of the Peterbilt 320 manage to soak most of the bumps and offer an adequate ride.
Since 2012, the Peterbilt 320 is available with two new steering gear options which offer a better handling for the congested traffic situations. The Sheppard HD94 offers front axle ratings up to 12,000 pounds, while the Sheppard SD110 offers front axle ratings up to 20,000 pounds.
Both steering gear options were tweaked to offer a ten percent wheel cut improvement (up to 40 degrees) compared to the previous models. Moreover, the turning radius is also significantly smaller while the serviceability was enhanced.
The Sheppard SD110 is available in several configurations for added flexibility namely a single gear rated up to 14, 600 pounds, a single gear with assist rated up to 20,000 pounds, or as a dual gear for either a left or right hand rated up to 20,000 pounds.
Peterbilt 320 Axle Ratings
Front Axle Rating
12,000 - 22,000 LBS
Front Axle Steer Rating – Tandem
Rear Axle Rating – Single
20,000 - 30,000 LBS
Rear Axle Rating – Tandem
38,000 - 60,000 LBS
Rear Axle Rating – Tridem
58,000 - 78,000 LBS
Thanks to its rugged design the Peterbilt 320 copes great with the arduous missions of the refuse and construction industries. Even is the cabin is not be the most ergonomic in the business, it’s still able to provide a high functionality and a satisfactory working environment. The truck is also available with multiple axle configurations and with a plethora of engines, while the hybrid model is an ideal option for those seeking for low emissions and smaller fuel consumption. Moreover, its cab over engine configuration gives it superior maneuverability around city while the GVWR (gross vehicle weight rating) of 51,000 lbs is also pretty generous.