Tata Hendrickson brings next-gen suspension systems
Hendrickson, the leading global manufacturer and supplier of medium and heavy-duty mechanical, elastomeric and air suspensions, had earlier introduced walking-beam tandem truck suspension. Later the company in its Chicago facility developed new suspension systems, based on the walking beam concept, called Haulmaax and Ultimaax, to elevate efficiency, productivity and safety of commercial vehicles. Its joint venture in India, Tata Autocomp Hendrickson Suspensions (THSL), launched the new suspension systems in India.
Made for India
THSL adapted the Ultimaax and Haulmaax suspension types for the Indian road conditions and market demand. “The Ultimaax and Haulmaax that we have introduced in India are capable of operating in Indian conditions which differ from the US. It was not an easy task. To ensure that both the suspension types succeeded in India, THSL employed a rigorous adaptation process. It could be described as re-developing them,” J V Narasimha Rao, VP, Business Development, THSL, said.
In 2013, Hendrickson borrowed aggregates like rear axles and other integrated components from Tata Motors. These were utilised to test the Ultimaax system on a few vehicles in the
US. THSL also purchased an LPK 2523.K 6x4 tipper from Tata Motors and fitted it with the Ultimaax suspension to demonstrate the delivery parameters. “We effectively showcased what the suspension could do. Work on the suspension began in 2014,” he said. Tata Motors carried out rigorous tests before rolling out 10 pilot CVs last April through its customers, based on their geographical spread and nature of operation. The pilots found their way to stone quarries, river beds, coal mines, and iron ore mines among others. “Some of the Ultimaax suspensionequipped trucks had clocked more than 3000 hours before the market roll-out,” he said.
The Ultimaax suspension employs the walking (equalising) beam concept with patented progressive rate spring and has found its way into the new Tata Prima 2525.K tipper with a 16-cu. m. body. The truck, aimed at construction and light mining segments, with Ultimaax as its rear suspension, promises a drastic reduction in maintenance needs and costs.
Claimed to be robust enough to withstand arduous working conditions, Ultimaax, in empty or light-load condition, has the shear springs to carry most of the vertical load. This results in a constant low spring rate and
Without an abrupt change in the spring rate, the ride and stability nature of the suspension changes to meet the application needs according to the variation in load. Reducing road shock and vibration, the suspension system improves the service life of the cab, chassis and body equipment. The inclusion of
a flat-bottom design enables Ultimaax to get the truck to profit from high ground clearance even under load.
For tippers, which work under tough conditions, high ground clearance is a necessity. Supported by rubber bushes in the front and rear, the suspension type also eliminates the need for periodic lubrication. It enables the truck to carry higher payload. The best part is the maintenance-free nature of Ultimaax.
Aimed at long-haul highway (truck) applications, the Haulmaax suspension type builds on successful trials across diverse geographies. Showcased on the Tata Prime 3718 10x2 haulage truck at Auto Expo 2018, the Haulmaax suspension type, according to Rao, will be introduced by Tata Motors on 2 other haulage trucks. These include the Tata Prima 3118 8x2 and Tata Prima 4923 6x4 prime mover. Marking a distinct departure from leaf spring suspension, the Haulmaax suspension type is rubber-based. It, along with the Ultimaax suspension type, is engineered to enhance productivity and comfort.
In addition to enhancing the productivity and comfort, the 2 suspension types are claimed to reduce driver fatigue as well. Elevating reliability and durability by a good deal, the 2 suspension types are lighter by 300 kg than a typical bogie suspension. With the shear springs and the progressive springs, the only bits that need maintenance, Ultimaax and Haulmaax offer a distinct advantage, Rao said. The maintenance procedure for shear and progressive springs involves checking them for signs of failure. The shear springs offer a softer unladen ride. The progressive springs enhance stability under load.
Unlike a conventional leaf spring suspension in a tipper or a haulage truck, which requires maintenance every 50,000 to 70,000 kms, the Ultimaax and Haulmaax suspension types have a set norm for spring replacement. The progressive springs have to be replaced once their height falls below 56 mm. Usually, when a tipper runs without load, and return to the pit, the rough surface over which it travels, leads to aggregate damage. In the case of Ultimaax, the damage to the aggregates due to excess movement and vibration is curtailed. Even if the driver drives at the same speed, the chances of damage are minimal. He can, in fact, do more trips as the comfort level goes up.
“We observed during the 9 months that we tested the suspension on the field that operators made at least 1 extra trip every day. If the operator is paid on per kg basis, he will earn more. Vehicle downtime for repairs and suspension maintenance will also go down,” Rao said.
The technology deployed to produce Ultimaax and Haulmaax has been patented by Hendrickson and includes thinner springs and a heat treatment process different from the one used to manufacture conventional leaf springs. “The bushes used in parabolic springs isolate the body from vibrations that are induced by the road surface. I would urge operators not to add leaves. Doing this will deteriorate the performance of a
conventional leaf spring suspension,” Rao said.
“Learning from Ultimaax validation cycle will be incorporated into the Haulmaax cycle. Haulmaax employs rubber bolster springs coupled with progressive load springs. The suspension type offers better performance in laden and unladen conditions,” he said.
Utilising elastomeric bolster springs and a progressive load spring (PLS) that work in synergy to provide outstanding ride quality when the truck is empty, Haulmaax works in such a way that the PLS engages and functions together with the elastomeric bolster springs as they compress to provide the additional stability vocational applications needed in line with the rise in load.
Like Ultimaax, the Haulmaax also deploys a distinct elastomeric spring design, which not only helps to provide an ideal balance of ‘empty’ ride quality and stability when loaded. It protects the chassis, cargo and body equipment from excessive vibration and road shock due to potholes and other road inconsistencies. Haulmaax weighs up to 400 kg lower than a vocational rear tandem suspension. The up to 400 mm of diagonal articulation of Haulmaax keeps the axle in contact with the surface below to ensure superior traction and better off-road mobility.
Confident of the advantages of Ultimaax suspension, Tata Motors has rolled out 100 CVs with it. These include a few units of the 2523.K tipper. Work is under way to fit the suspension type to Tata 2518. Once done, it will mark an entry into the mass market. Justifying the cautious approach of Tata Motors towards the adoption of the suspension type, Rao said “if we upscale at the first instance, issues could arise. For us, they would translate into capability or supply chain challenges. Tests are being performed also on Signa 2518 and 2523. These 2 are highvolume products.”
Emphasising on the success of its 6-tonne lift axle that has found its way to the Tata LPK 3118 and 3718, he said they are working with Tata Motors to develop a 10-tonne lift axle suspension for 10x2 and 6x2 trucks and tankers. “We unnecessarily run all the axles on the road. We are therefore working on a 10-tonne lift axle suspension for tankers and bottle carrier segments. We are also aiming at tippers. This will benefit them as the difference between a laden and unladen vehicle is too high,” he said.
After the introduction of an advanced lift axle suspension for the Tata 3718, the company is also working on a new lift axle design. Slated for introduction in 2019, the new lift axle will be superior and offer more benefits. THSL is also working with Daimler India Commercial Vehicles to equip its BharatBenz trucks with a lift axle. The model being considered is the 3123R. Aware of the efforts CV OEMs are taking to keep the costs down, and in a post-BS IV scenario, THSL is working closely with many OEMs to help them cut weight. “A suspension weighs about 450 kg. A 10% weight reduction will be a significant change,” Rao said.
Haulmaax is aimed at longhaul, highway segments
V Narasimha Rao, VP - Business Development, THSL is confident of Ultimaax and Haulmaax elevating efficiency, service life, safety and payload capacity.
Ultimaax is robust, and engineered to withstand arduous working conditions that CVs like tippers are subjected to.