A power-unit product already on the market is the Spicer Central Tire Inflation System, which Dana acquired from Eaton several years ago. It automatically reduces air pressure to enhance carrying ability off-road, then pumps up the tires when trucks return to pavement. It's more costly, but operators of commercial logging and concrete-mixer trucks have found it can enhance off-road travel without resorting to front-driving axles.
7. Brake changes
Another trend affecting axles and suspensions are changes in new federal stopping distance requirements, which mean higher-torque front brakes or disc brakes being used on the steer axles.
“The additional torque that translates into the steer axle knuckles and beam must be handled effectively,” notes Dana's Slesinski. “The Dana Spicer Steer axles have a strong forged steel I-beam with patented power-rib to handle these increased demands.”
Disc brakes also are being driven by demand for trailers that require less maintenance, says Rick Rickman, vice president of sales for Ridewell. Disc brakes require less frequent maintenance than drum brakes, and when routine maintenance is required it can be accomplished more quickly.
“We have seen the premium cost of disc brakes over drum brakes come down significantly in the past several years, which has resulted in the value of reduced maintenance quickly providing a payback for the higher initial cost,” Rickman says.
Haldex also notes that fleets are demanding spring brakes that are easier to install accurately. That's why it now offers Gold Seal and Life Seal spring brakes with the OEM-specified welded clevis pushrod assembly for truck-tractor and trailer manufacturers. These new models come with the clevis welded to the pushrod and in the exact pre-set position used in new vehicle production.
Vocational market trends
Trends in severe-service markets indicate a continuing move toward air suspensions, says Hendrickson's David McCleave, director of sales and marketing. Hendrickson offers a premium severe-service air suspension, PriMaax EX. In more severe vocations where payload is more of a concern than fuel economy, products like Hendrickson's Haulmaxx rubber suspension can offer up to 900 pounds of weight savings compared to competitive suspensions.
“For instance, for vocations like the refuse industry, weight savings directly translate to route consolidation and optimization, which greatly adds to the bottom line,” McCleave says.
On the other hand, vocational and specialty trucks still use a high percentage of steel spring suspensions, and even van trailers have seen a shift back to more steel spring, mechanical suspensions, notes Reyco Granning Senior Vice President Ray Mueller.
“Initial cost and reduced maintenance are the most common reasons given,” he says. “It's another example of how the trucking industry often values simplicity, durability and low cost over advanced technology.”