Sterling’s HX chassis design

It may not quite qualify as a model change, but Sterling’s new HX chassis design includes so many enhancements, refinements and improvements that it comes close.

The HX chassis was originally designed to make room for the bigger engines required by the the new emissions regulations, but designers didn’t stop there. In addition to new frame section heights and improved frame strength ratings, the engineers designed a modular frame mounting grid and added a new air-ride cab suspension, an improved radiator and cooling system, a scroll type air-conditioning air compressor, a high-pressure steering box, new fuel tanks and new front and rear suspension options.

Frame rail choices
The new frame rails offer section heights from 10 to 11 inches plus a super-deep, 13-inch version. With optional inserts the new frames can be spec’ed with RBMs of up to 5 million inch pounds.

The frames are also laid out with what the company calls its Optilock Chassis Grid System. Essentially this means that the holes for any component mounting are arranged in a pre-determined grid. Using the grid template you can mount two components opposite each other, one on the inside and one on the outside of a frame rail without having to worry about the bolt holes interfering with each other. The holes can be pre-punched for specific components at the factory or created by your body builder. New, thicker cross members and gussets add additional beef and rigidity to the frame.

Taking the bumps out of the road
For improved motion control and more comfort, Sterling’s simplified Comfort Ride air cab mounting with its beefed up air shocks and torsion sway control offers improved service life and lowers the cost of operation. Under the wheels, the front suspensions now include both taper-leaf springs rated to 20,000 pounds and multi-leaf designs up to 23,000 pounds in addition to maintenance-free suspension designs with ratings up to 14,600 pounds.

Optional 12,000-pound rated lightweight composite springs will now be offered for the A-line with a savings of 77 pounds per truck. And the Sterling Airliner suspension family will include a new front air suspension.

Rear suspension options for the HX include the Hendrickson Primaxx air suspension system for heavy-duty vocational trucks, the Haulmaxx walking beam rear suspension and an enhanced TufTrac two-stage suspension for improved ride quality when the truck is unladen.

Keeping cool
Borrowing a page from high-end automobiles, Sterling is using a scroll type compressor for the cab air conditioning. These have fewer moving parts and greater durability compared to piston-type compressors. The engine radiator has also been redesigned with plastic end cabs and aluminum fins for lighter weight and better cooling. Radiator braces were also optimized for rigidity and strength. Radiator options include a 1,000-inch, cross-flow design with or without in-tank oil coolers, and 1,200-inch and 1,400-inch cross-flow radiators.

A new THP60 high-pressure steering box from TRW offers a more compact shape and greater wheel cut angles. Weight-reducing cylindrical aluminum fuel tanks will now come standard on the Sterling A-Line and L-Line trucks in 23-inch and optional 25-inch diameters.