Caterpillar® Product Information
Performance Report May 1997
Cat® 793B vs. 793C Cat
Job Study Purpose
To assess the performance and fuel consumption of the Caterpillar ® 793C Mining Truck and compare it to the Caterpillar 793B.
Study
February 17-20, 1997
Location
Southwestern U.S. Open Pit Copper Mine
Material
Blasted waste and ore rock with an estimated density of 2,700 lb/LCY
Field Data
Dave Berry - Peoria Proving Grounds Bruce Fickett - Tinaja Hills Training Center P. Craig Gardner - Construction Mining Truck Marketing Tim Lemons - Construction Mining Truck Marketing Dave Monroe - Corporate Mining Group Mike James - Rust Tractor Terry Sheean - Rust Tractor
For Dealer Sales Personnel
Executive Summary
Caterpillar conducted this study to provide a production and fuel consumption comparison of the 793C versus the 793B. Engineers weighed and timed the trucks on three haul profiles (uphill loaded, downhill loaded, and flat loaded) to determine their productive capabilities. Overall, the 793C outperformed the 793B on all haul profiles by demonstrating an average 15% improvement in the downhill cycle and a 5% improvement on the uphill and flat cycles. Fuel consumption per ton of material moved was less for the 793C as well. On average, the 793C used 8% less fuel on downhill cycles, 6% less on uphill cycles, and 4% less on flat cycles.
Equipment Summary
793C
793B
830,000 lb.
830,000 lb.
2,300 hp
2,160 hp
3516B
3516A
Average Empty Weight
321,200 lb.
321,500 lb.
Average Loaded Weight
836,800 lb.
820,800 lb.
193 yd 3
193 yd3
40.00R57
40.00R57
<2,000 smu
<8,000 smu
Rated Gross Machine Weight Gross Horsepower Engine
Body Volume Tires Machine Hours
Study Description
Caterpillar engineers set up computerized, electronic load-cell scales for weight measurements. A Caterpillar engineer rode in each truck cab recording both cycle times and fuel burned at marked points along the truck cycle. The engineers used digital stop watches calibrated in minutes and hundredths of minutes to time the cycles. They used Caterpillar Service Tool fuel meters installed on both trucks to measure fuel consumption. All hauls originated at a common loading face. The loading tool, a P&H 4100 cable shovel with a 56 yd3 bucket, was a three pass match for the trucks. Three haul profiles were selected for the evaluation, called “Uphill loaded”, “Downhill loaded”, and “Flat loaded”. A brief description: Distance Vertical Rise
2
Uphill 5,541 ft 505 ft
Downhill 5,621 ft –505 ft
Flat 4,916 ft –28 ft
Engineers in the cab logged all delays, breaks, or wait times and eliminated those times from analysis. Observers on the ground in the load and dump areas recorded data in those parts of the cycle. All scale weights were matched to each cycle and included related weight, time, and on-board fuel meter data. Prior to the test, engineers conducted a review of the haul roads to determine the location of speed traps used to calculate grade horsepower. They also verified the horsepower settings of the engine and overall performance of the trucks. Both trucks checked out to be within ± 3% of nominal specifications during the test. The 793B was 2% above and the 793C was 1% above nominal specification. This report is based directly on the measured data from the truck study with no adjustments. Due to the moving face and dump area an average of the load and dump times were assumed for each truck to minimize impacts on either truck during the cycles. The following tables indicate actual production as it occurred during the study. Due to dump and face movement an average was used for each of these areas for both the 793C and 793B. By removing these areas of the cycle, only the segment of the haul and return were examined. Production figures are shown in tons per hour. Haul Condition
Discussion of Results
Actual Production
793C
793B
Advantage
Downhill
1,261.1 t/hr
1,098.2 t/hr
15%
Uphill
1,039.9 t/hr
990.7 t/hr
5%
Flat
1,820.5 t/hr
1,739.7 t/hr
5%
Caterpillar Service Tool fuel meters installed on each truck measured fuel consumption. These meters use a turbine sensor on the fuel supply and return lines to provide a digital read-out of fuel consumption in the cab. The read-out was in U.S. gallons and indicated continuous, cumulative fuel burned. Consumption figures shown below are in tons per gallon. Haul Condition
Fuel Consumption
793C
793B
Advantage
Downhill
16.56 t/gal
15.61 t/gal
8%
Uphill
33.06 t/gal
30.44 t/gal
6%
Flat
45.65 t/gal
44.10 t/gal
4%
3
Speed Trap Analysis
The haul cycles were segmented to include speed traps. The downhill loaded haul included two speed traps. The uphill loaded and flat loaded hauls included one each. The speed traps were used to calculate grade horsepower. The calculation requires taking the time to move through a specified distance and grade, given a specified weight, to determine the horsepower the truck is developing. With the use of fuel meters, cross checks of expected horsepower readings can be done. The hauls and speed traps were surveyed with GPS for accuracy. Rolling resistance was estimated to be 0.7% - 1.7%. Data gathered for each truck was very consistent.
Conclusions
This study indicates that the 793C is considerably more productive than the 793B. The 793C showed advantages in improving production while decreasing fuel consumption. The gains in fuel efficiency can be attributed to improvements in the 3516 B Series engine. This engine has a 6.5% higher horsepower rating which can account for the 5% - 15% production improvements. In this study, the 793C met or exceeded all machine specifications and exceeded performance expectations. Both trucks exhibited power train efficiencies expected of a mechanical power train. These trucks demonstrated the ability to put 82-84% gross engine horsepower to the ground. They were equipped with lighter than standard weight bodies which allowed the trucks to carry higher than rated tonnage without exceeding gross machine weight ratings. Using the lighter weight bodies allowed for normal deviation of payloads while maintaining production expectations and without exceeding critical gross machine weights.
4
Appendix A Cycle Times and Fuel Consumption Flat Loaded Cycle Time (min) 793B
793C
Fuel (gal)
Index
793B
793C
0.93
10.93
3.05
13.11
1.32
11.32
Index
Load Area
3.08
3.08
Haul
1.99
1.93
Dump Area
2.25
2.25
Return
1.55
1.48
95
1.23
11.39
113
Total
8.87
8.74
99
6.53
16.75
103
Payload (tons) Production (ton/hr)
249.65 1,688.7
97
102
257.9
103
Avg. Fuel Burn (gph)
44.2
46.34
105
1,770.5
105
Tons per Gallon
38.2
38.21
100
The 793C had faster cycle times and moved more material per hour. The increased production could be attributed to higher run out speeds in 6th gear. The increased production was produced with no additional fuel consumption when looked at on a tons per gallon basis.
Cycle Times and Fuel Consumption Downhill Loaded Cycle Time (min) 793B
793C
Fuel (gal)
Index
793B
793C
0.93
10.93
0.11
0
1.32
11.32
Index
Load Area
3.08
3.08
Haul
5.01
3.87
Dump Area
2.25
2.25
Return
3.3
3.07
93
5.84
15.55
95
13.64
12.27
90
8.2
7.8
95
Total Payload (tons) Production (ton/hr)
249.65 1,098.2
77
—
257.9
103
Avg. Fuel Burn (gph)
36.1
38.14
106
1,261.1
115
Tons per Gallon
30.44
33.06
109
In the downhill cycle the results demonstrated faster cycle times and more tons moved per gallon of fuel. The 793C was able to maintain one gear faster going downhill than the 793B. This improvement is attributed to the improved efficiencies of the design of the hydraulic circuits and increased air flow through the radiator due to faster fan speeds.
5
Cycle Times and Fuel Consumption Uphill Loaded Cycle Time (min) 793B
793C
Fuel (gal)
Index
793B
793C
0.93
10.93
13.55
13.28
1.32
11.32
Index
Load Area
3.08
3.08
Haul
7.6
7.26
Dump Area
2.25
2.25
Return
2.19
2.29
105
0.19
10.04
21
15.12
14.88
98
15.99
15.57
97
Total Payload (tons)
249.65
Production (ton/hr)
990.7
96
98
257.9
103
Avg. Fuel Burn (gph)
63.5
62.78
99
1,039.9
105
Tons per Gallon
15.61
16.56
106
The results demonstrate faster cycle times and more tons moved per gallon of fuel. The 793C numbers were as expected in relation to the 6% increase in horsepower. The fuel consumed was less than expected and attributed to the improvements of the 3516 B Series engine.
The information contained herein is intended for circulation only to Caterpillar and dealer employees whose duties require knowledge of such r eports and is intended exclusively for their information and training. It may contain unverified analysis and facts observed by various Caterpillar or dealer employees. However, effort has been made to provide reliable results regarding any information comparing Caterpillar built and competitive machines. Effort has been made to use the latest available spec sheet and other material in the full understanding that these are subject to change without notice. Any reproduction of this release without the foregoing explanation is prohibited.
TEXR0269 May 1997 © 1997 Caterpillar Printed in U.S.A.
