Picking a Suitable Truck © Dr. B. C. Paul 2000 Revised 2009 Hi!

The Rear Dump Truck

Truck Configurations l Rear Dump Solid bed elevates and dumps material over the back l Solid bed can take abusive handling and loading Can be lined Traditional liners steel Carbon composites now Lighter bed liners avoid loss of payload

Variations l Most manufactures offer different bed for different material weights Coal and iron ore for example l Trucks are sized by weight and volume - most limiting controls productive service Like to get both to limit at same time

Maneuverability Issues l Back dumping forces drivers to back into spaces blind l Most rear dumps are two axle with double tires on rear - fair maneuverability l Some very large have had double rear axle - hard to turn l Articulated versions are smaller but highly maneuverable - often have flotation tires for soft underfoot

The Tree Axle Rear Dump

Rear Dump Power l Have relatively high HP to payload ratios makes very gradable gas mileage marginal makes best for short in pit hauls l Generally geared low so 42 mph typical peak speed l Weight centers on drive tires for traction (can have 4 wheel drive)

Powering Haul Trucks l Diesel Engine (common in US) gas guzzlers frequently around 1 mpg l Trolly Electric Rare in U.S. because it limits mobility to areas with developed lines l Trolly Assist Keeps down engine size boost power on steepest grade Loosing ground because full electric drive systems loosing to mechanical

Three Axle Bottom Dump l More of a tractor trailer arrangement - open top and bottom opens to unload More popular with lighter material like coal because of bed bottom abuse issues l More of vehicle is hauler less power to payload larger bed relative to size

The Three Axle Bottom Dump

Properties of Bottom Dumps l Geared higher for more speed l Gives poor gradability SMCRA limits most ramps to 10% anyway l Speed and payload to power favors longer hauls - coal to processing facility l Have lower loading height - works better with FELs

Impact of Bottom Dump l Can’t stand impacts l Allows truck to use regular truck dump Dump time may be 25% of rear dump l Material must be free flowing and not prone to freeze l Three axles tend to maneuver poorly

Getting the Best of Both Worlds l Two Axle Bottom Dump l Improved Maneuverability l Looks like a three axle body only solid and on two axles l Has Intermediate Power to Payload ratio l Bottom dump still means light free flowing non freezing material

Two Axle Bottom Dump

My Considerations l My Benches are relatively narrow so I would like maneuverability – favors rear dump l The Hauls are moderate length with some steep grades and rolling resistance on the sand dunes – favors high power to payload, again rear dump l Oil Shale is kind of heavy and blocky, could beat on truck bed – one piece beds of a rear dump would be handy l I’ll pick a rear dump

Turns Out That Was Also The Choice of the Problem l You have been assigned to pick the trucks and loaders for President Ahmadinejad’s “Truck fleet of International Peace and Love”. The following trucks are to be considered l Cat 769D Dual Slope l Cat 773E Flat Floor l Cat 777D Flat Floor l Cat 789D Dual Slope l Cat 793 C Dual Slope l (Specifications for all these trucks are available in the 35th Edition of the Cat Handbook) l It is often very handy to have your truck specs available – a copy of the Cat Handbook is great

Reading Cat Specs Truck Model Truck Data Label Numerical Values

Truck Weight Basic Body and Chasis Is 70,706 lbs Total truck weight and Payload can be 157,000 lb (78.5 tons) I could carry a load of 86,294 lbs (>43 tons) But if I use a bedliner it Will cut my payload By 7280 lbs And leave me with 79,094 lb payload (<40t)

A Truck Can Be Limited By Weight or Volume If I heap the truck it can Handle 31.7 yd^3 (but that could mean a High load at the middle Of the truck Struck even with the top Is 21.6 yd^3

Truck Size Width 16’8” For 2 way traffic you would Probably want a road 2.75 times this 1/4 th truck width Probably want about 1.5 times width For single direction traffic

Loading Height Loader will have to be Able to get over 10’2” To get over the side of The truck (that does not guarantee It can heap the truck)

Turning Corners Clearance to turn a full Circle is 66’7”

Traction Games How much of the weight Is on the drive wheels Can control traction When the truck is empty 50.3% of its weight is On the rear drive wheels When full 66.7% is on The rear drive wheels Of course you can put 4 wheel drive on but that Is pricey to buy and Pricey to maintain

More Considerations l I would like a big truck so I can minimize the number of trucks I have to run l Problem is that big trucks have a big turning radius and I have a narrow bench Need to consider how I will load for maneuvering