Greater automation for second generation Bell ADTs

According to Bell Equipment Marketing Manager: Europe, Ian Marshall, Tier 3 engines are already being installed in Bell-manufactured trucks destined for Europe and the Hitachi markets of the Asia Pacific. However, they will continue making use of the Tier 2 engines in the South African market for the foreseeable future.

Commenting on the Tier 3 engines, he said: “Fortunately Bell Equipment makes use of a very advanced diesel engine supplier like Mercedes Benz whose emissions technology is at the forefront of our industry and the engines they supply are extremely clean and fuel efficient. The Tier 3 engines look virtually identical to their predecessors and the power and torque ratings remain unchanged. Importantly we are still the ‘lowest cost per tonne’ manufacturer as our fuel burn figures have not been significantly affected as has been the case in general with the implementation of other Tier 3 diesel engines.”

Marshall added that the upgrades on the Generation 2 D-series ADTs are predominantly “under the skin” changes, with no real impact on the exterior of the truck. The drivetrain, chassis, suspension and other systems on the Bell D-series have been tweaked and refined with a view towards improving reliability, increasing performance and productivity as well as enhancing the ergonomics of the trucks.

According to Electrical Design Engineer, Pieter Goosen, the “under the skin” changes to the electrical systems include the introduction of new body controllers to run all non-engine/transmission functions on the truck. “This has enabled us to improve diagnostics and include the fan drive and suspension control units into these new controllers. The electrical system is, therefore, less complex and has fewer components,” he said.

Cab comfort is key

More noticeable are the changes to the interior of the cab, which has been completely re-designed and refitted making use of scratch resilient composite materials that are more robust and durable.

The instrument panel has been replaced with its more up-to-date successor, featuring newer technologies such as stepper motor gauges, LED warning lights rather than globes and a dot matrix screen as opposed to a LCD screen. Goosen explains the benefits thereof: “This allows more information to be displayed at one time and provides more readable menus. The diagnostics have also been improved so that more information can be displayed. For example, when a fault code appears the operator can press the ‘select’ button for detailed on screen information so that troubleshooting can be done immediately.”

The new instrument panel has enabled the power socket and diagnostic connector to be moved closer to the landing area, which has been enlarged to enable the operator to house items such as a clipboard and cell phone.

Goosen added that all switches are now centrally grouped on a single touch pad or Sealed Switch Module (SSM). This includes the retarder lever and the controls for the air conditioning unit, which now features climate control thanks to two temperature sensors positioned in the evaporator unit to measure airflow into and out of the cab. The beauty of the SSM is that it is a CAN-controlled unit and has only four wires to control 46 functions and 20 switches. The benefit of this reduced wiring is better reliability and ease of use as the SSM is also used as a number keypad for certain menus.

Other cab improvements include the repositioning of the relays, circuit breakers and radio from the roof panel to a position at the left hand side of the operator for better access and easier service and maintenance. The demist vents are more rugged and the positioning thereof has been optimised. The front windscreen bonding area has been increased and a rear windscreen wiper option is now available.

Operator comfort and ease of use were two of the key criteria for cab upgrades and for this reason the steering wheel adjustment clearance has also been improved along with the cooler box temperature control and the seat adjustment clearance.

A further enhancement to the cab is the new seat that boasts an improved design to reduce whole body vibration with fore and aft damping as well as vertical isolation for greater operator comfort.

Intelligent tipping with ‘I-Tip’

An improved hydraulic block across the Bell ADT range has reduced residual pressure to effectively decrease fuel burn and reduce noise in the cab. Improved hydraulic hose routing and a simpler brake pedal are geared to improve reliability and offer easier servicing and maintenance. Likewise a simplified pneumatics system has improved the commonality of pneumatics systems throughout the range and has succeeded in reducing the parts count.

However, most importantly, the new hydraulic block has paved the way for the introduction of an electro-hydraulic tip function with an “I-Tip” programmable control and tip cylinder soft stops.

The innovative “I-Tip” system links the accelerator, neutral button on the transmission, the soft stop on top of the hydraulic cylinders, the park brake and the bin-tip lever – all of which are monitored and controlled by the electronic chassis control module of the ADT.

Bell Equipment ADT Product Designer: Hydraulics and Pneumatics, Francois Stander explains the beauty of the system: “An operator can choose from several combinations of those functions for tipping. The default is the same as before when the operator manually engages all the functions during the tipping cycle. Alternatively an operator can select a combination of two or more of the functions. For example, when he tips he would hold the tip lever into the bin raising position and the transmission would go into neutral, the park brake would be engaged and the engine would rev to its maximum rpm. Near the top of the bin tip stroke the hydraulics are controlled to ensure a soft cushioned stop.

“Similarly for the bin down cycle the operator would push the bin tip lever down into the lower position and the detent feature would hold the lever in position. The operator could release the park brake button, select drive and the truck will move off in first gear until the bin angle reaches 50 degrees whereupon the truck transmission will select second gear. When the bin is at 15 degrees the transmission selects third gear and when the bin is fully down the truck can reach fourth or any other gear,” he said.

Marshall added that the “I-Tip” system offers a greater level of automation which makes Generation 2 Bell ADTs even easier for unskilled drivers to operate and gives skilled operators more time to concentrate on the more important aspects of their work.

Meanwhile drivetrain enhancements include the fitting of new transmissions into both the smaller and larger Bell ADTs. The transmissions have increased memory size for better statistical collection of data. Transmission control has also advanced to offer more refined adaptive shifting to improve clutch life and shift quality.

The Generation 2 Bell B35D and B40D have the new Allison Generation 4 4500 transmission. In the larger models the shift and clutch controls have also been improved for better operator comfort and the C3 and C4 clutches have been redesigned using thicker reaction plates to improve reliability. The retarder valve body material is now aluminium to reduce corrosion and the retarder is controlled by software for better retarder control.

The drivetrains of the smaller Bell ADTs, from the B18D to the B30D, now make use of the new ZF Ecomat 2 Plus transmission. Features of this cooler running package include improved internal sealing, a modified electro-hydraulic control unit, internal plastic and gasket materials adapted to cope with higher temperatures. Shift and clutch control are also improved.

Further drivetrain enhancements, specific to the smaller Bell trucks, include an all aluminium cooling package. According to Bell Equipment ADT Product Designer, Karl Heine the new package is a simplified system with no remote transmission cooler. As a result the total parts count of the cooling system has been reduced by over 40% and the new air/oil transmission cooler provides greater cooling for better retarder performance.

Bell Equipment Machine Shop Research and Development Manager, Dave Heaney said: “Bell has also developed its own limited slip differential, unique to the Bell B30D, to offer a more reliable and stronger product. Fully enclosed wet disc brakes have also been developed for this model and will be offered as an option later in 2006 and as an option for the B25D as from 2007.

“Wet disc brakes are essential for muddy, wet conditions and will provide a longer service life and stronger performance. The life expectancy of the Bell wet disc brakes is in excess of 10 000 hours and a special feature is the self contained cooling system that alleviates the need for remote oil cooling.”

Improvements to the D-series suspension were made with Whole Body Vibration (WBV) legislation in mind. This legislation has been drafted and is in the process of being implemented in parts of Europe in particular.

On all models the damping on the gas/oil struts on the front suspension have been improved for better operator comfort. The assembly procedure has likewise been simplified to improve reliability.

Bell Equipment believes that it has improved operator comfort by 25% as well as improved reliability by re-designing the panhard link mountings and the Y-link on the front suspension of the B30D and smaller models. The new Y-link has an extra spherical bearing to reduce vibration and shock transfer.

The front chassis of all models has been updated with improved structural and weld detail for increased reliability and durability.

According to Bell Equipment Structural Design Engineer, Robert Dent, the structural development team has spent the last few years refining and improving the structural components across the ADT range including the bin and chassis. Using state of the art Finite Element Analysis technology, together with field data, this team was able to make significant improvements to most of the structural components. Zooming into the finer details of these components, while maintaining proper basic principles of structural design, was key to significantly improving the life expectancy of structures. These design improvements were then confirmed using thorough test and verification processes.

In general a significant amount of testing has gone into the development of the Generation 2 Bell ADTs including tests carried out by independent companies such as Mira to ensure compliance with international legislation as well as accelerated testing on key components such as the cooling package.

Bell engineers have spent over a year testing the engine, hydraulics and electric controls on the trucks in various applications on three continents.

Comments Marshall: “Bell Equipment prides itself on manufacturing industry-leading automated ADTs and the attention to detail shown during the Generation 2 D-series upgrade has meant we have been able to take the quality of our product and our level of automation to new heights.”

A major functional upgrade in the G2 cab is the sealed switch module which groups all switch functions on a simple keypad.