Hydrosteer performs Freightliner C120 Century Class twin steer conversion

HYDROSTEER: Master steering gear and draglink.
HYDROSTEER: Master steering gear and draglink. Contributed

HYDROSTEER carries one of Australia’s largest range of heavy vehicle power steering products. Their range covers new and re-manufactured power steering gears, steering pumps, VIP steering wheels, steering slip shafts, coolers, mitre boxes and draglink assemblies that are made to stringent OE standards.

Hydrosteer are also setup to carry out installations and repairs with fully-equipped workshops in 3 locations throughout Australia and highly trained technicians, making them a prime choice within the industry.

Recently a request came through to Hydrosteer to convert a C120 Freightliner from a single steer prime mover to a twin steer 8 x 4, and the company stepped up to the challenge.

The Conversion:

Initially, the customer’s dealership removed the front axle and replaced it with two Hendrickson Air Tec Axles prior to delivery to the Hydrosteer branch in Bayswater (Victoria).

The Hydrosteer engineering department went into overdrive to ensure the engineering specifications, Ackerman angle and design work was completed to meet the required delivery date.

The original steering system was designed for a single steer configuration, so Hydrosteer had to inspect and hydraulically test all components. From these tests it was determined existing steering gears could not be used without major modification for a twin steer application.

Hydrosteer’s large data base and product range allowed them to find the best-suited steering system components for the application while utilizing as many of the original components as possible. The company decided on the use of R.H.Sheppard M100 master and slave gears, which also enabled the use of double ended pitman arms.

Once the gear and pitman arm selection was made, the original steering gears were removed and the new gears fitted. This system design had to take in a number of considerations including wheel cut, bump steer, exhaust clearance, oil flow rates, fluid back pressure, operating temperature ranges and interference from all steering components as they move from lock to lock.

An adapter plate was designed and manufactured by Hydrosteer to mount the slave steering gear onto the chassis rail. The adapter plate design had to be suitable to support the mechanical loads exerted by the steering system for the life of the vehicle.

After the steering gears and pitman arms were in place it was time to measure and manufacture the custom adjustable drag links and slip shaft, all of which were made in-house then fitted and wheel cuts adjusted.

Finally with all components fitted, the hydraulic circuit was plumbed in with an oil cooler fitted. The moment of truth, the reservoir was filled, system bled and engine started up.

A full hydraulic test was completed and relief plungers set in the master steering gear. All of the flow and pressure requirements were too specification during the initial test and the vehicle was ready for road testing.

During the road test the vehicle exceeded all testing criteria and performed fantastically, which led to a very happy customer. The customer made comment on the quality of workmanship as he was unable to see where any modifications had been made. It appeared to be a standard factory vehicle, driven straight off the lot.

HYDROSTEER: The work in progress.
HYDROSTEER: The work in progress. Contributed
Big Rigs

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