Little Big Shot

LITTLE BIGSHOT

The new UD Croner has a certain beefiness to its presence that suggests it is, in essence, a scaled down version of its Quon big brother. This notion is confirmed by the specifications which show striking similarities between the two models.

UD’s new Croner could be considered something of a crossover between medium- and heavy-duty. It comes in two distinct variants: A medium-duty PK 18 280 4x2 with a Gross Vehicle Mass (GVM) of 17.5 tonnes; and the PD 25 280 6x2 with a GVM of 24.5 tonnes, the latter slotting into the light end of the heavyduty market. Both iterations have a Gross Combination Mass (GCM) of 32 tonnes. These Croners represent the latest phase of a marked step change in the UD lineup. It started with the larger Quon, overall displaying the fruits of a big investment by parent company Volvo Group to make these trucks as technologically advanced and bullet-proof as possible. As such the new Croner receives a number of key features that stem directly from the Volvo technology stable, not least the willing GH8E six-cylinder engine with a capacity of 7.7 litres, bore and stroke measurements of 110mm x 135mm and a compression ratio of 17.5:1. This is, in fact, the same powerplant that’s used in the 8.0 litre Quon range.

UD Croner delivers torque that belies its stature.

Much like the rest of the truck, this engine has a ‘big truck’ feel about it and delivers 206kW (280hp) at 2,200 rpm and 1,050 Nm (774lbft) of peak torque from a super low 1,100 rpm. Importantly, maximum torque remains rock steady from 1,100 to 1,800rpm. Japanese OEMs have not been dubious about developing a heavy duty offering on a medium duty platform and UD has, in more recent years, made it clear they are comfortable with a shift of focus to what it describes as the bottom end of the heavy duty segment. The Croner’s power profile straddles these two categories boosted by a high pressure common-rail fuel injection engine. It achieves Euro 5 emissions standards using Selective

Catalytic Reduction (SCR). Fuel and Adblue tank capacities are 255 and 50 litres respectively. Coupled to the engine is a six-speed Allison 3000 Series torque converter automatic featuring push-button gear selection and Gen 5 Adaptive Shift Control. The decision to eschew Volvo Group’s Common Architecture and Shared Technology (CAST) has helped to reduce tare weight which will enhance its appeal in emerging markets like those in the Middle East, Africa and Southeast Asia, which were identified early on when the development of the Croner as a replacement program for the long-serving Condor medium-duty range commenced in 2013. The Croner has twin overdrive ratios

Up to four additional cameras can be connected to the multimedia unit.

of 0.75 and 0.65 respectively and a first gear ratio of 3.49. Along with a torque converter stall ratio of 1.98:1, the transmission features two power take-off (PTO) provisions on the left and right side with maximum torque capacities of 660Nm when using one or 930Nm in total when both are used in tandem. It’s perhaps this combination of factors that have brought it to the attention in recent months of Australia Post, which has reportedly purchased 40 new Croners across its general post and B2B StarTrack divisions. At the back end of the vehicle is a choice of either multi-leaf spring or electronically controlled two-bag air suspension (PK) and four-bag (PD) with a programmable remote control (ECAS4) mounted in the cab to control raise and lower functions. The drive axle has a ratio of 5.57:1 and a ground capacity of 11 tonnes on the PK and 18 tonnes (with the addition of the lazy axle) on the PD, while the front axle, supported by parabolic leaf springs, has a ground capacity of 6.5 tonnes. Somewhat surprisingly, unlike its disc brake equipped Quon sibling, the Croner defers to the time-honoured Japanese medium-duty tradition of drum brakes which are full-air with automatic adjusting S-cams along with anti-lock (ABS) and electronic brakeforce distribution (EBD). Continuing the big truck theme, wheels are full-size 22.5” 10-stud items with a 335mm pitch circle diameter (PCD) – which is the standard size used with heavy-duty European trucks – shod with Bridgestone 295/80 R22.5 and 11R 22.5 rubber on front and rear wheels respectively. The chassis width is 850mm, with rails measuring 236mm x 70mm x 8.0mm constructed from rolled high-tensile steel — combining maximum strength with light tare weight. Meeting ECE-R29 crash protection standards, the cab is spring suspended with double-acting shock absorbers and the driver’s seat is air-suspended with adjustable shock absorber, recliner, height control and left armrest. Safety features include a driver’s airbag and seatbelt pretensioner. The 6.1” touchscreen CD/DVD player includes truck specific satellite navigation, digital radio, Internet radio (requires phone data), USB port, auxiliary port, micro SD slot, phone tethering, Bluetooth, PDF reader, and is Wi-Fi enabled. Croner also features a comprehensive telematics system with in-cab GSM and GPS unit with SIM card connected to a roof antenna. A 12-month subscription is included which enables monitoring of fuel consumption and environment positioning, total operational time and distance, average speed, total CO2 emissions, vehicle utilisation, driver anticipation and braking behaviour, engine and gear utilisation, speed adaptation and idle time. Factory fitted optional equipment includes low-profile 275/70 R22.5 tyres, Alcoa aluminium wheels, a 6.17:1 rear axle ratio, vertical exhaust stack and custom paint colours. Dealer fitted options include up to four additional cameras connected to the multimedia unit (in addition to the standard reverse beeper and digital infrared reversing camera with microphone), Tyre Pressure Monitoring System (TPMS), reverse sensors (high or low fitment) and a wireless phone charging pocket in the dash centre. In sum, the Croner PK 18 280 and PD 25 280 exhibit the traditional UD hallmarks of tough, reliable, no-nonsense trucks. Going by the specifications, both possess the ability to perform a variety of roles with the generous GCM rating of 32 tonnes meaning the PK would be capable of towing a pig trailer with an Aggregate Trailer Mass (ATM) of 14.5 tonnes while loaded to its maximum GVM of 17.5 tonnes. Above all, the substantial nature of the engine, driveline and running gear bodes well for a long and productive service life with manageable whole of life costs, regardless of the application.

UD is manufacturing Croners at its Thailand facility.

Fuso 4x4 engages diff locks in rugged terrain.

UNLOCKING POTENTIAL

The differential lock plays a vital role in maintaining drivability of a vehicle in adverse conditions. Without it the vehicle would be unable to traverse tricky environments often found in off-road situations.

One of the ground-breaking left and right axles to revolve at different other wheel which has more traction. inventions associated speeds when the vehicle was turned Diff locks, on the other hand, come in with early industrial and from the dead ahead course. The sharper two distinct styles: Driver Controlled automotive development the turn the more difference in speed and Automatic Locking — of which the was the differential, or diff for short. between both axles. venerable Detroit Locker is arguably the Initially the engineers and inventors of This, however, created an issue in that most auspicious. the day came up with crude methods to if a wheel lost traction due to slippery The Detroit Locker is an automatic deliver the torque from the power source conditions it automatically received most locking differential that is designed to the driving wheels, including chain of the engine’s torque due to the ‘path to lock both rear axles together when drive and worm gear drive systems. of least resistance’ principle. The other torque is applied and the vehicle is In 1827 a Frenchman by the name of wheel receiving next to no torque was travelling in a straight line. During turns, Onésiphore Pecqueur is said to have therefore rendered useless even if it was the unequal speed of the wheels forces invented a differential that was first on a hard surface. disengagement, thus allowing them to used on steam-driven vehicles. By the To overcome this problem a number turn at different speeds. time internal-combustion engines of measures were devised including the Originally named the Thornton NoSpin started appearing towards the end of the limited-slip differential (LSD) and the Differential, it was patented by Ray 19th century, it was reportedly a well- diff lock. Thornton in 1941, and initially developed established component. The LSD is typically considered for 6x4 (tandem drive) truck applications. Logically named from its ability to something of a compromise between an It was manufactured by the Detroit provide a ‘differential’ in speed between open (standard) diff and a fully lockable Automotive Product Corporation and the two axles, the differential concept was diff. It often features a series of clutch used in American military vehicles during devised by incorporating a pinion and friction discs and plates that are held WWII. crown wheel to enable a 90-degree turn apart by springs and forced together by After the war and into the 1960s, the in the torque delivery path, along with centrifugal force when a wheel breaks Thornton NoSpin was original equipment a planetary gear set. This enabled the traction, thus diverting the torque to the on many American light and medium

duty trucks – earning it the nickname Detroit Locker – and at this point drag racers and high-performance car enthusiasts started using it. The Detroit Locker’s major internal pieces are the side gears, outer springs, drivenclutch assemblies, spider assembly and centre cam. The centre cam is held in the spider assembly with a snap ring and is free to rotate. The spider assembly takes the place of spider gears found in a conventional open differential. The locking effect comes from a series of teeth on the spider assembly and the driven clutches on either side of the spider. The driven clutches are located between the side gears, which are splined to the axles and therefore turn at the same speed as the axles. When the vehicle is under power both axles are locked in position and turn at the same speed. During a turn, the centre cam inside the spider gear locks into position and acts as a ramp to disengage the driven-clutch teeth from the spider gear. This allows the outside wheel to rotate faster around the corner. When both wheels are again travelling at the same speed, the exterior springs force the teeth to mesh and resume their locked status. Early Detroit Lockers had a reputation for loud mechanical noise when turning corners, a feature that has been moderated on later versions. In 2005, powertrain giant Eaton Corporation purchased Detroit Locker’s parent company and greatly expanded the offering. The Driver Controlled Diff Lock (DCDL), sometimes called cross lock, is widely used on heavy vehicles and uses a dog clutch arrangement – usually activated by a pneumatic solenoid – that locks the differential gears and axles together as a solid unit. Tandem drive units have an additional locking device within the power divider or inter-axle differential (IAD). This mechanism is mounted on the forward diff which enables varying axle speeds to occur between the forward and rear drive axles during turns. With the IAD locked and both DCDL units engaged, all drive wheel groups in a tandem drive truck are compelled to turn in unison. This is extremely useful when traversing

Diff lock use is common in vocational applications where environs may have shifting surfaces. muddy or boggy ground, but drivers must be sure to disengage all locks before resuming dry bitumen road driving to avoid damaging the diffs, driveline and tyres. Furthermore, if diff locks are engaged the vehicle will not turn corners easily, which can pose a safety risk. The general consensus from prominent truck axle manufacturers is that the IAD lock and DCDL should only be used at speeds under 40km/h during adverse road conditions such as rain, snow or gravel/dirt roads, and then only until conditions improve to enable sufficient traction with the locks disengaged. An important point to note is that cross locks and the IAD lock should never be engaged while there is wheel slip or spin occurring as this can seriously damage the mechanism. It’s also recommended that DCDL are not engaged when the vehicle is descending steep grades as potential loss of vehicle stability could result in a jackknife of the prime mover and trailer. The trick prior to travelling on adverse road surfaces is to flick the switch, either while stationary or travelling at a slow constant speed, and then ease up on the accelerator momentarily to reduce torque on the gearing and let the locks engage. It’s the same procedure for unlocking, with the diff locks unlocked first while still at slow speed, followed by the IAD lock. With most trucks, an indicator light and in some cases an additional audible warning come on to remind the driver that the locks are engaged. While for many interstate trucks diff locks are rarely needed, for those in vocational applications involving off-road work such as tippers and logging trucks, they are relied upon on a daily basis. In these applications the modern marvels of diff locks and central tyre inflation systems enable powerful trucks to maintain traction while hauling massive weights up steep grades on dirt or gravel tracks. Without them, these feats simply wouldn’t be possible.