SME
Construction Engineering
Equipment productivity
Use this for “A 14 m³ truck hauls 3.2 km at 25 km/h and returns at 40 km/h; loading, spotting and dumping take 6.5 min. At 50 working minutes per hour, what does it move each hour?”
Chart
Load, spot and dump: 6.5 min
Haul: 7.68 min
Return: 4.8 min
This is an example. Type your own values to start a new problem.
q
Truck capacity
example · m³
tf
Fixed time
example
d
Haul distance
example
vₕ
Loaded speed
example · km/h
vᵣ
Empty speed
example · km/h
tₕ
Haul time
calculated
tᵣ
Return time
calculated
tc
Cycle time
calculated
E
Working minutes
example · min/h
P
Production
calculated · m³/h
Formulas
tₕ
=
60
×
d
vₕ
7.68
=
60
×
3.2
25
tᵣ
=
60
×
d
vᵣ
4.8
=
60
×
3.2
40
tc = tf + tₕ + tᵣ
18.98 = 6.5 + 7.68 + 4.8
P
=
q
×
E
tc
36.88
=
14
×
50
18.98
Assumptions
•
Speeds are averages over the whole road, loaded and empty, speeding up and slowing down included.
•
The fixed time tf covers loading, spotting and dumping; it does not change with the haul distance.
•
E is the working minutes in each hour; 50 min/h is a common job efficiency.
•
Production is loose volume; multiply by the load factor LF for bank volume.
Step-by-step
WE KNOW
q = 14 m³, tf = 6.5 min, d = 3.2 km, vₕ = 25 km/h, vᵣ = 40 km/h, E = 50 min/h
FIND
haul time (tₕ), return time (tᵣ), cycle time (tc), production (P)
Step 1 · Find haul time (tₕ)
Use tₕ = 60 × d ÷ vₕ
Distance over speed is the haul time in hours; 60 minutes per hour turns it into minutes.
tₕ
=
60
×
3.2
25
tₕ
=
192
25
tₕ = 7.68 min
Step 2 · Find return time (tᵣ)
Use tᵣ = 60 × d ÷ vᵣ
Distance over speed is the return time in hours; 60 minutes per hour turns it into minutes.
tᵣ
=
60
×
3.2
40
tᵣ
=
192
40
tᵣ = 4.8 min
Step 3 · Find cycle time (tc)
Use tc = tf + tₕ + tᵣ
One cycle is the fixed time plus the trip out loaded and the trip back empty.
tc = 6.5 + 7.68 + 4.8
tc = 18.98 min
Step 4 · Find production (P)
Use P = q × E ÷ tc
E
tc
is
how
many
times
the
truck
cycle
fits
in
the
working
minutes
of
each
hour;
each
time
moves
one
load
q
.
P
=
14
×
50
18.98
P
=
700
18.98
P
=
36.88
m³/h
Check
Put the numbers back in. Both sides should match.
7.68
=
60
×
3.2
25
✓
4.8
=
60
×
3.2
40
✓
18.98 = 6.5 + 7.68 + 4.8 ✓
36.88
=
14
×
50
18.98
✓
Topic check
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