Loading and Hauling Cycle Time Fixed Time Variable

Loading and Hauling

• Cycle Time = Fixed Time + Variable Time – Fixed Time = spot time, load time, maneuver time, Dump time – Variable Time = travel time – Resistance • Total Resistance = Rolling Resistance + Grade Resistance • Rolling Resistance due to tire flexure and surface penetration • Grade Resistance due to grade of incline

• Rolling Resistance • • 40#/ton on hard surface rubber tired 30#/ton if radials T 4 -1 Rolling Resistance increases 30#/ton/1” penetration • Rolling Resistance Factor = 40# + (30# * inches penetration) • Rolling Resistance = Rolling Resistance Factor * tons

• Grade Resistance • % of vehicle weight acting parallel to incline surface • Negative going downhill Positive going uphill • 20#/ton • Grade Resistance Factor = (20# * % grade) • Grade Resistance = Grade Resistance Factor * tons • Effective Grade (%) = % Grade + Rolling Resistance/20

Altitude • 3% power loss per 1000 ft • Using turbocharger allows power to stay constant up to 10, 000 ft

Traction • Power available to move vehicle – Rimpull – used for wheeled vehicles • Pull available at rim of driving wheel – Drawbar pull – used for tracked vehicles • Power available at hitch – Maximum usable pull = coefficient of traction * wt on driven wheels (for tracked vehicles and all wheel drive vehicles this is total wt) – T 4 -2

• Performance Curve – Maximum speed for a given load F 4 -1, 4 -2 • Retarder curves – Maximum speed going downhill in gear

Travel Time • Cannot use max speed – Need to account for start up and stop – Average speed factors T 4 -3 – Max spd * Ave spd factor = speed for haul

Dozers • Tractor w/ front mounted earthmoving blade – Crawler • Low ground pressure (6 – 9 psi) • Excellent traction – Rubber tired • Hi spd • Can compact soils • Can operate on paved surfaces

Dozers • Attachments – Rakes, scarifiers, rippers – tow compactors, scrapers, wagons – Blades • F 4 -7, F 4 -8 • Performance based on power vs blade size • Hp/ ft of cutting edge -> blades ability to penetrate hard soils • Hp/loose cy -> blades ability to push soil

Production – 5 bullets pg 96 show to determine blade volume – Blade load (LCY) = 0. 0139 HWL – Fixed cycle time – maneuver, change gears, start loading, dump – Variable time – time to doze and return – Can decrease by using reverse to return – T 4 -4, 4 -5

– Job Management – Downhill dozing • Increases blade load • Cycle time reduction – Slot Dozing • Increases blade capacity up to 50% – Blade to Blade • 2 dozers together • Combined capacity > 2 x 1 dozer

• Care for tracks and undercarriage – Must keep tracks clean – Must keep undercarriage clean and in good repair – Don’t run at hi spd over rough terrain – Minimize turns – Try to balance left and right turns and up & down slope operation

Loaders • • • Tractor with a front end bucket Wheeled or tracked Excavate soft – medium hard material Load hoppers and haul units Stockpile material, backfill ditches Moving material

Loaders – Wheel Loaders • High mobility • Not all terrain but low ground pressure • Modern are articulated F 4 -9 – Tracked Loaders • Can operate in most soils and on steeper slopes • Slower over longer haul distances=> less productivity F 4 -10 – Backhoe loader F 4 -11 – Attachments – augers, snow blades, forklifts, dozer blade, crane booms

Skid Steers • • Small wheeled loader w/ rigid axles Steers by braking wheels on one side <10, 000# weight Lift capacities of 600 – 6300 # Can also be tracked List of attachments pg 100 Also mini excavators

Material Handlers • • • Rough terrain forklifts Common Lull Max lift 9000# Max height > 60 ft Move materials around site Eliminates hand carrying or use of other equipment for carrying

Loader Production • Average Bucket load x cycles per hour – Cycle time = loading, dumping, making 4 reversals in direction, traveling minimum distance T 4 -6, F 4 -14 – Bucket Capacity is heaped T 3 -1 and use fill factor T 3 -2 – Ex 4 -7

Job Management – Cutting tires major problem – L-5 tires – rock extra deep tread should be used when dealing with shot rock – Keep water out – lubricates rock /rubber cutting – Need to know tipping load – may limit amount of material in bucket – Loader size & productivity based on site limitations