In the nineties, caterpillar first identified the need for larger graders for maintaining haul roads used by heavy-duty haul trucks. Having paved the way (excuse the pun) with their 785 (150t), 789 (180t) and 793 (240t) class trucks, they were well progressed in developing their class topping 797 (at the time 327t), when in 1996 they introduced the Cat 24H.
The largest of all H Series graders, this turbo charged machine stood in a class of its own, effectively stamping its authority as the mining machine of choice, when grading haul roads of medium and large mine sites. Remaining unchallenged, this machine has continued to evolve with the introduction of the 24M in 2007 and most recently the 24, heralding Cat's new generation of products that now exclude the letter modifier that we've all become so used to (another story for another day perhaps).
So, what's so good about this one? If we were to play 'buzz word bingo', this grader ticks all the right boxes with improvements across safety, operator acceptance, durability, versatility and reliability. Thus, if we start with the assumption that this machine incorporates the latest bells and whistles, too broad for the scope of this article, it is perhaps most appropriate, that I focus on the key differences that define this machine from its predecessor.
To begin with, its heavier, gaining an 11% increase in weight, to sport a 'typically equipped' mass of circa 73t. The addition of these kilos has resulted in greater blade down pressure and increased traction, allowing this machine to maintain a more consistent ground speed, when carrying a larger load on the 7.3m moldboard, working on grade, or turning under load.
Repowered with Cat's C27 ACERT engine, this grader now also has considerably more power than the smaller C18 previously used, resulting in a 15% improvement in low-end torque when compared with the M. Not bad, given the upsizing now prolongs the target rebuild life of the engine by an estimated 33%, that when coupled with a modular approach in design, has improved component changeouts times by up to 70%, in the case of the transmission and cooling package.
Unlike the graders of 'yesteryear' (and yes, I realise that was not all that long ago!) that were operated by lever and wheel, today's machines are operated via joystick control. Albeit the early resistance when introduced by Cat in their M Series graders in 2007, this method of operation has achieved widespread acceptance globally.
Interestingly, this technology has led to a 78% reduction in hand and wrist actions, that when paired with Caterpillar's Cat GRADE with Cross Slope systems, has improved operator productivity and haul road quality, resulting in lower truck tire wear, decreasing rolling resistance as well as reducing premature tyre failure; music to all ears, especially the number crunchers that sit in windowless rooms of ivory towers...
This article was originally published by the Components Only team in the July - August 2018 issue of "@ The Coal Face" magazine.Published 24 July, 2018