Big Dog Mining

Truck Cycle Time & Fleet Match

How long one haul cycle takes, how many trucks it takes to keep the loader busy, and what the fleet actually produces. Pick a truck class and a material and the specs, speeds and cycle times fill themselves in from published tables.

Step 1: The truck

Choosing a class fills in payload and top speed. Override either if you have the spec sheet.

Truck class ?

Payload capacity auto ?t

Rated payload weight, not body volume.

Top speed auto ?km/h

Flat-out maximum. Average speed is derived from it.

Body type ?

Sets dump time and typical spot time.

Body heaped volume (optional) ?

Leave blank to size by weight only. Fill it in for light material.

Step 2: The loader filling it

The loader sets how long a truck sits under the bucket, which sets the whole fleet size.

Material ?

Bank density auto ?

Weight of 1 m³ still in the ground.

Swell auto ?

1 m³ in the ground becomes this many m³ loose.

Loader bucket ?

Heaped rated capacity.

Bucket fill factor auto ?

How full the bucket really gets.

Digging class auto ?

Sets the loader cycle below.

Loader cycle time auto ?s

Seconds for one bucket pass.

Truck spot time auto ?min

Minutes to maneuver under the bucket.

Step 3: The haul road

Distance and road condition set the travel legs, which are usually most of the cycle.

One-way haul distance ?

Loader to tip, one way. Both legs are counted.

Road surface ?

Sets rolling resistance.

Grade, loaded direction ?%

Positive = loaded uphill. Sustained max is 8-15%.

Road and traffic conditions ?

Where in the published speed range your road sits.

Step 4: The fleet

How many trucks you actually have, and how well the operation is run.

Trucks assigned to this loader ?

Compare against the matched number below.

Job conditions ?

Floor, muck pile, room, weather.

Management ?

Operators, discipline, delays, maintenance.

Extra wait and delay per cycle (optional) ?min

Only for delays not already in efficiency. Usually zero.

Truck owning & operating cost per hour (optional) ?$ / h

Per truck. Gives cost per ton hauled.

cycle time, minutes

trucks to match the loader

bank tons / hour

Step	Value	Where it comes from

The haul circuit

Where the cycle time goes

Speed factors: turning top speed into average haul speed

Haul section length	ft	Loaded, starting from stop	Unit already in motion
0–107 m	0–350	0.25–0.50	0.50–2.00
107–229 m	350–750	0.35–0.60	0.60–0.75
229–457 m	750–1,500	0.50–0.65	0.70–0.80
457–762 m	1,500–2,500	0.60–0.75	0.75–0.80
762–1,067 m	2,500–3,500	0.65–0.75	0.80–0.85
over 1,067 m	over 3,500	0.70–0.85	0.80–0.90

SME Mining Reference Handbook, 2nd ed., Table 12.3, p. 296 (after Bishop 1968). The calculator uses the starting from stop column for the loaded leg, because a haul cycle begins stationary under the loader. The empty return uses the same table's footnote: 0.55 / 0.60 / 0.65 of top speed under 152 m (500 ft), and 0.75 / 0.80 / 0.85 beyond it, for unfavorable / average / favorable conditions. Note that a factor can exceed 1.00 on a very short section if the truck enters it already at speed.

Rolling resistance by road surface

Ground surface	Equivalent extra % grade
Gravel, well compacted, dry, free of loose material	2.0
Gravel, not firmly compacted but dry	3.0
Gravel, loose	10.0
Mud with firm base	4.0
Mud with soft spongy base	16.0
Sand, loose	10.0
Snow, packed	2.5
Dirt, smooth, hard, dry, well maintained, free of loose material	2.0
Dirt, soft, unplowed, poorly maintained	4.0
Dirt, soft plowed	8.0
Dirt, deeply rutted	16.0

SME Mining Reference Handbook, 2nd ed., Chapter 13 (Haul Roads), p. 327. Rolling resistance is added to the real grade to give total resistance, which is what you check against the truck's rimpull chart.

Off-highway rigid-frame truck classes

Payload, t	Payload, st	Tires	Empty, kg	GVW, kg	Top speed, km/h
36	39	18.00R33	35,460	71,214	74
44	49	21.00R33	37,888	82,100	80
53	59	24.00R35	49,312	102,739	68
62	68	24.00R35	50,103	111,810	68
92	102	27.00R49	72,412	164,654	68
133	147	33.00R51	116,482	249,476	56
183	202	37.00R57	141,249	324,318	58
226	249	40.00R57	159,755	386,007	61
290	320	53.00R63	231,332	521,631	60
318	350	56.00R63	252,651	570,165	64
363	400	56.00R63	260,815	623,689	68

SME Mining Reference Handbook, 2nd ed., truck specifications by gross vehicle weight, p. 320. The printed table gives every weight twice, in kilograms and in pounds, so each kilogram figure here was checked against its own pound figure by conversion. That is how three wrong digits in the machine transcription of this table were caught and corrected.

Passes to load a rigid-frame truck: a cross-check

Truck, t (st)	15 m³	20 m³	25 m³	35 m³	45 m³
136 (150)	5	4	3	n/a	n/a
181 (200)	6	5-6	4	3	n/a
217 (240)	n/a	n/a	6	5	3-4
290 (320)	n/a	n/a	n/a	6	4-5
360 (400)	n/a	n/a	n/a	n/a	6

SME Mining Engineering Handbook, p. 937. Use this to sanity-check the pass count the calculator works out. Three to six passes is the range these tables are built around; if you land outside it, the truck and the loader are not well matched.

What this does not know. Average speeds here come from published factors on the truck's top speed, not from your truck's rimpull curve. On a long, steep, badly maintained climb the real loaded speed can be well below the factored figure. The calculator shows you total resistance for both legs so you can check it against the manufacturer's rimpull chart, and if the two disagree, trust the chart and type the speed in yourself.

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Worked example

Worked with the values this page loads with, so the method can be checked against the cited source without entering anything. Change any input above and the calculator recomputes; the numbers below stay as a fixed reference case.

7.4
3.3
1064

Passes to fill by payload weight	4.16	Eq. 12.24a, p. 303
Passes to fill by body volume	not checked	no body volume entered
= passes used (rounded)	4 passes	limited by weight (no body volume given)
Load per truck	25.4 bank m³	Eq. 12.25, p. 303
Load per truck	59.6 t	× bank density 2.35 t/m³
Loader cycle per pass	33.0 s	M-H, medium-hard digging, 11.5 m³ bucket
Spot time	0.45 min	overlaps loading (Eq. 12.26a)
Spot + load time (T_l)	2.20 min	Eq. 12.26, p. 303-304
Loaded average speed	52.7 km/h	top speed × 0.775, Table 12.3 p. 296
Travel out, loaded	1.70 min	Eq. 12.18: 1500 m ÷ (v × 16.7)
Dump time	1.00 min	rear dump, p. 304
Empty average speed	36.5 km/h	top speed × 0.800, Table 12.3 footnote 2, capped by downgrade speed limit
Travel back, empty	2.46 min	Eq. 12.18
= theoretical cycle (T_ch)	7.37 min	Eq. 12.19, p. 298
+ extra wait and delay	0.00 min	none entered
= corrected cycle (TC_ch)	7.37 min	Eq. 12.20, p. 298
Trucks to match the loader	3.35	Eq. 12.27: T_ch ÷ T_l, p. 304
Operating efficiency	0.73	job Good / management Good, p. 302
Rate if trucks are the limit	1064 t/h	Eq. 12.21 with 3 trucks
Rate if the loader is the limit	1187 t/h	one load per T_l
= production	1064 t/h	the lesser of the two: trucks bound
Total resistance, loaded leg	10.0%	8.0% grade + 2.0% rolling, p. 327
Total resistance, empty leg	-6.0%	check both against the rimpull chart

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Estimating aid only. This is not an engineering design and not a substitute for the judgment of a competent or qualified person. Verify every result against the cited source and your own site conditions. Full terms and disclaimer.