Machine models

Cat 789C specifications

789C control modules, overload behavior and refill compartments

The 789C's transmission/chassis controller and brake controller have different jobs. A shift restriction can be commanded by payload management, while an oil quantity may describe only a tank. Identify the command and compartment before treating either observation as a failed component or a complete-system refill requirement.

The C-series electronics changed from the earlier B-series truck

The July 2005 training introduction identifies separate Transmission/Chassis and Brake ECMs on the 789C. The former replaces EPTC II and also controls the hoist. The Brake ECM combines ARC and TCS functions, with TCS diagnostics accessible through the Cat Data Link and ET service tool.

The same introduction locates the transmission hydraulic tank separately from the hoist, brake and converter tank. These circuits are not one interchangeable reservoir. Its folded-core radiator description also explains why an individual core replacement can appear in a service record without replacement of the entire radiator.

Original SERV1706-01, July 2005, pp7–9: controller changes, separate hydraulic tanks and radiator construction

ARC retarding and TCS wheel intervention answer different demands

The original brochure describes retarder control managing downhill speed while maintaining engine speed for cooling. Traction control instead responds to a slipping driven rear wheel. Record whether the truck was descending or losing traction; calling both events a transmission slip would conceal the different control actions.

Its service table gives the crankcase 291 litres, or 77 US gallons. The inherited engine-oil entry of 20 gallons belongs to the transmission hydraulic tank in that edition. The complete transmission hydraulic system has its own quantity including that tank.

Use the serial-specific maintenance procedure to establish the required service operation.

Original AEHQ5321-01: brake/control descriptions and p18 compartment-specific service-refill table

A payload limit can deliberately restrict the transmission

Caterpillar's January 2002 payload-manager document explains that an overload detected during second-gear weighing can limit the truck to second gear and reduce engine and automatic-retarder speed settings. The restriction remains until the load is dumped. Its example for a different truck must not become a 789C payload rating.

The document identifies 789C 2BW00303 and later as factory-equipped from May 2000, and an earlier flashable-controller population eligible for retrofit. A badge alone therefore does not prove the installed software or configured overload setting. Obtain the actual VIMS configuration and event record when investigating this specific combination of speed and shift limits.

Original TELQ3749-01, January 2002, pp1–5: second-gear weighing, limit response and 789C implementation/retrofit table

789C corrected fields and retained earlier entries — Earlier capture, corrected quantity and document scope
Field	Earlier entry, rejected for this label	Corrected record
Engine Oil Capacity	20 gal	77 gal (US); Crankcase; 291 L in AEHQ5321-01 Original manufacturer document
Torque Converter/Transmission System - Including Sump	20 gal	59 gal (US); Transmission hydraulic system including tank; 224 L in AEHQ5321-01 Original manufacturer document
Torque Converter - Transmission Sump	59 gal	20 gal (US); Transmission hydraulic tank; 76 L in AEHQ5321-01 Original manufacturer document
Hydraulic System Fluid Capacity	140 gal	140 gal (US); Brake/converter/hoist hydraulic tank; 531 L, not the whole hydraulic system Original manufacturer document

Entries in this reference
Listing-entry count
1

Short answer

Cat 789C: rigid rock truck.

Selected configuration figures
Configuration	Documented field and quantity
789C	Gross Power 1,900 hp Pump Flow - High Idle 193 gpm

789C specification matrix — Dimensions and weight
Specification	789C
Overall Length	39.92 ft
Overall Width	25.18 ft
Overall Height	20.25 ft
Wheelbase	18.68 ft
Ground Clearance	3.83 ft
Dump Height	39.25 ft
Dump Ground Clearance	4.37 ft

Dump
Specification	789C
Dump Angle	49.5 degrees
Load Capacity - Struck	102 yd3
Load Capacity - Heaped	137.34 yd3
Rated Payload	390,000 lb
Lower Time	17.3 sec
Raise Time	18.9 sec

Engine
Specification	789C
Number Of Cylinders	16
Engine Model	3516B EUI
Gross Power	1,900 hp
Net Power	1,770 hp
Power Measured @	1,750 rpm
Aspiration	Turbocharged
Displacement	4,211 cu in
Bore	6.7 in
Stroke	7.5 in
Net Power - ISO 9249	1,791 hp
Net Power - SAE J1349	1,771 hp
Net Power - 80/1269/Eec	1,791 hp
Gross Power - SAE J1995	1,900 hp

Operational
Specification	789C
Fuel Capacity	851 gal
Cooling System Fluid Capacity	175 gal
Engine Oil Capacity	77 gal (US)
Diff And Final Drive Fluid Capacity	154 gal
Steering System Fluid Capacity	50 gal
Brake/Hoist System Fluid Capacity	240 gal
Hydraulic System Fluid Capacity	140 gal (US)
Operating Voltage	24 V
Alternator Supplied Amperage	75 amps
Tire Size	37.00-R57(E4)

Transmission and speeds
Specification	789C
Transmission Type	Six-speed planetary power shift with direct injection
Number Of Gears - Forward	6
Number Of Gears - Reverse	1
Max Speed	32.7 mph
Reverse	6.5 mph
Forward - 1	7.2 mph
Forward - 2	9.8 mph
Forward - 3	13.2 mph
Forward - 4	17.8 mph
Forward - 5	24.2 mph
Forward - 6	32.7 mph

Steering
Specification	789C
Steering Standards	SAE J1511 OCT90 ISO 5010:1992

Weights
Specification	789C
Empty Weight	299,101 lb
Loaded Weight	700,000 lb
Weight Distribution Front - Empty	47 %
Weight Distribution Rear - Empty	53 %
Weight Distribution Front - Loaded	33 %
Weight Distribution Rear - Loaded	67 %

Tires
Specification	789C
Standard Tires	37.00-R57 (E4)

Brakes
Specification	789C
Brake Surface - Front	12,662 in2
Brake Surface - Rear	18,024 in2
Standards	SAE J1473 OCT90 ISO 3450:1996

Body Hoists
Specification	789C
Pump Flow - High Idle	193 gpm
Relief Valve Setting - Raise	2,500 psi
Body Raise Time - High Idle	18.9 s
Body Lower Time - Float	17.3 s
Body Power Down - High Idle	15.6 s

Final Drives
Specification	789C
Planetary Ratio	10.83:1
Differential Ratio	2.35:1
Total Reduction Ratio	25.46:1

Operating Specifications
Specification	789C
Top Speed - Loaded	32.7 mph
Steer Angle	36 degrees
Body Capacity - SAE 2:1	137 yd3
Turning Diameter - Front	90.2 ft
Nominal Payload Capacity	390,000 lb
Turning Circle - Clearance Diameter	99.2 ft

Service Refill Capacities
Specification	789C
Cooling System	175 gal
Differential - Final Drives	154 gal
Steering Tank	34 gal
Steering System - Including Tank	50 gal
Brake Hoist System - Includes Tank	240 gal
Crankcase	77 gal
Brake/Hoist Hydraulic Tank	140 gal
Torque Converter/Transmission System - Including Sump	59 gal (US)
Fuel Tank - Standard	851 gal
Torque Converter - Transmission Sump	20 gal (US)

Weight Distributions Approximate
Specification	789C
Front Axle - Empty	47 %
Front Axle - Loaded	33 %
Rear Axle - Empty	53 %
Rear Axle - Loaded	67 %

Weights Approximate
Specification	789C
Chassis Weight	218,300 lb
Gross Machine Operating Weight	700,000 lb
Body Weight Range	26 800-29 950 kg (59,000-71,500 lb)

Capacity Dual Slope 100% Fill Factor
Specification	789C
Struck	96 yd3
Heaped (SAE 2:1)	137 yd3

Capacity Flat Floor 100% Fill Factor
Specification	789C
Struck	102 yd3
Heaped (SAE 2:1)	158 yd3

Suspension
Specification	789C
Effective Cylinder Stroke - Front	4 in
Effective Cylinder Stroke - Rear	3.5 in

Approximate Weights Dual Slope
Specification	789C
Body	59,625 lb
Chassis	225,500 lb
Gross Weight - Empty	310,525 lb
Full Liner	20,840 lb
Tail Extension	1,700 lb
Side Boards	2,860 lb

Approximate Weights Flat Floor
Specification	789C
Body	66,200 lb
Chassis	225,400 lb
Gross Weight - Empty	299,100 lb
Grid Liner	3,300 lb
Rear - Third Liner	4,200 lb

Ratios
Figure	789C
Engine horsepower per 1,000 lb of weight	5.9
Fuel tank per engine horsepower	0.48 gal
Rated payload per cubic yard of heaped body	2,840 lb

Reference directory classification
Equipment group	rigid rock truck

Where the 789C ranks in Cat's list — Scope of the captured comparison
Brand	Equipment group	Compared entry	Sort order
Cat	rigid rock truck	789C	Descending quantity; 1 is largest

Figure	789C	Rank	Lowest in line	Highest in line
Engine power	1,770.0 hp	9 of 24	450.0 hp	4,000.0 hp
Listed weight	299,101 lb	4 of 14	66,500 lb	584,225 lb
Fuel capacity	851.0 gal	7 of 22	140.0 gal	1,800.0 gal
Horsepower per 1,000 lb	5.9 hp	12 of 14	5.8 hp	10.1 hp
Rated payload	390,000.0 lb	5 of 14	79,000.0 lb	793,664.0 lb

The 789C beside its neighbours
Base version	785 Bare Chassis	789C	789
Engine power	1,600 hp	1,770 hp	2,100 hp
Weight	789C: 299,101 lb
Fuel capacity	785 Bare Chassis: 410 gal (US); 789C: 851 gal
Wheelbase	789C: 18.68 ft; 789: 57,000 mm
Rated payload	789C: 390,000 lb

History and service record of 789C

Caterpillar's first 150-ton-class truck. The 789 line began in 1986 as Caterpillar's first model in the 150-ton payload class, built to reduce the haulage bottlenecks large open-pit mines were running into as pit operations scaled up; the 789C sits in that lineage between the original 789 and the truck's later generations. Grokipedia, Caterpillar 789.
The 1,900 hp rating carried forward. The 789C's 1,900 hp gross engine rating is the same top-end figure Caterpillar still offers as an option on the current 789 lineup, which is why the C-series' power output has not felt dated even as the payload and electronics around it have moved on. Caterpillar, 789 Mining/Haul Truck product page.

789C: forum references — Forum-title search
Forum index	Equipment class queried	Names in the search	Matching titles
Heavy Equipment Forums	rigid rock truck	Cat and the 789 line that the 789C belongs to (no title names the exact model). That is too few titles to say what owners mostly ask about, so the most recent are listed instead	1

CAT 992 Loading Rear End Dump CAT 789 (Heavy Equipment Forums, 2011-11-11)

Used market for the 789C — Dated first-page listing snapshot
Observation date	Listing source	Equipment search	Listings
2026-09-24	MachineryTrader	Cat rigid rock truck	10

Model	Listed	Model years	Lowest asking	Highest asking	Median asking	Median hours
789C	10	2005 to 2010	$146,706	$146,706	$146,706	14,833

789C: recall reference — Dated CPSC search
Search date	Database	Names queried	Search result
2026-09-24	U.S. Consumer Product Safety Commission	Cat together with the rigid rock truck 789C	No matching recall in this search

Sources for this page
Evidence class	Document, classification and recorded date
Reference site	Reference site: Cat 789C — RitchieSpecs. Observed 2026-09-24.
Forum threads	Forum threads: Heavy Equipment Forums thread index for Cat 789C — Heavy Equipment Forums. Observed 2026-09-24.
Published history	Published history Source: Grokipedia, Caterpillar 789 — Grokipedia. Observed 2026-09-27.
Published history	Published history Source: Caterpillar, 789 Mining/Haul Truck product page — Caterpillar. Observed 2026-09-27.
Used-market listings	Used-market listings: MachineryTrader listings for Cat 789C — MachineryTrader. Observed 2026-09-24.
Federal agency data	Federal agency data: Recall database search for Cat — U.S. Consumer Product Safety Commission. Observed 2026-09-24.

Cat 789C: Configuration records

789C

Specification	Source figure
Operating Specifications
Body Capacity - SAE 2:1	137 yd3
Nominal Payload Capacity	390,000 lb
Engine
Gross Power	1,900 hp
Net Power	1,770 hp
Displacement	4,211 cu in
Number Of Cylinders	16
Engine Model	3516B EUI
Bore	6.7 in
Stroke	7.5 in
Net Power - ISO 9249	1,791 hp
Net Power - SAE J1349	1,771 hp
Net Power - 80/1269/Eec	1,791 hp
Gross Power - SAE J1995	1,900 hp
Aspiration	Turbocharged
Power Measured @	1,750 rpm
Transmission and speeds
Number Of Gears - Forward	6
Max Speed	32.7 mph
Transmission Type	Six-speed planetary power shift with direct injection
Number Of Gears - Reverse	1
Reverse	6.5 mph
Forward - 1	7.2 mph
Forward - 2	9.8 mph
Forward - 3	13.2 mph
Forward - 4	17.8 mph
Forward - 5	24.2 mph
Forward - 6	32.7 mph
Final Drives
Planetary Ratio	10.83:1
Differential Ratio	2.35:1
Total Reduction Ratio	25.46:1
Service Refill Capacities
Cooling System	175 gal
Differential - Final Drives	154 gal
Steering Tank	34 gal
Steering System - Including Tank	50 gal
Brake Hoist System - Includes Tank	240 gal
Crankcase	77 gal
Brake/Hoist Hydraulic Tank	140 gal
Transmission hydraulic system including tank — Manufacturer 789C document; source edition retained	59 gal (US) [source]
Fuel Tank - Standard	851 gal
Transmission hydraulic tank — Manufacturer 789C document; source edition retained	20 gal (US) [source]
Body Hoists
Pump Flow - High Idle	193 gpm
Relief Valve Setting - Raise	2,500 psi
Body Raise Time - High Idle	18.9 s
Body Lower Time - Float	17.3 s
Body Power Down - High Idle	15.6 s
Suspension
Effective Cylinder Stroke - Front	4 in
Effective Cylinder Stroke - Rear	3.5 in
Tires
Standard Tires	37.00-R57 (E4)
Steering
Steering Standards	SAE J1511 OCT90 ISO 5010:1992
Weights Approximate
Chassis Weight	218,300 lb
Gross Machine Operating Weight	700,000 lb
Body Weight Range	26 800-29 950 kg (59,000-71,500 lb)
Weights
Empty Weight	299,101 lb
Loaded Weight	700,000 lb
Weight Distribution Front - Empty	47 %
Weight Distribution Rear - Empty	53 %
Weight Distribution Front - Loaded	33 %
Weight Distribution Rear - Loaded	67 %
Dimensions and weight
Overall Width	25.18 ft
Overall Height	20.25 ft
Wheelbase	18.68 ft
Dump Height	39.25 ft
Dump Ground Clearance	4.37 ft
Dump
Load Capacity - Struck	102 yd3
Load Capacity - Heaped	137.34 yd3
Rated Payload	390,000 lb
Dump Angle	49.5 degrees
Operational
Fuel Capacity	851 gal
Tire Size	37.00-R57(E4)
Cooling System Fluid Capacity	175 gal
Crankcase — Manufacturer 789C document; source edition retained	77 gal (US) [source]
Diff And Final Drive Fluid Capacity	154 gal
Steering System Fluid Capacity	50 gal
Brake/Hoist System Fluid Capacity	240 gal
Brake/converter/hoist hydraulic tank — Manufacturer 789C document; source edition retained	140 gal (US) [source]
Operating Voltage	24 V
Alternator Supplied Amperage	75 amps
Approximate Weights Dual Slope
Full Liner	20,840 lb
Tail Extension	1,700 lb
Side Boards	2,860 lb
Approximate Weights Flat Floor
Grid Liner	3,300 lb
Rear - Third Liner	4,200 lb
Additional specifications
Overall Length	39.92 ft
Ground Clearance	3.83 ft
Raise Time	18.9 sec
Lower Time	17.3 sec
Brake Surface - Front	12,662 in2
Brake Surface - Rear	18,024 in2
Standards	SAE J1473 OCT90 ISO 3450:1996
Top Speed - Loaded	32.7 mph
Steer Angle	36 degrees
Turning Diameter - Front	90.2 ft
Turning Circle - Clearance Diameter	99.2 ft
Front Axle - Empty	47 %
Front Axle - Loaded	33 %
Rear Axle - Empty	53 %
Rear Axle - Loaded	67 %
Struck	96 yd3
Heaped (SAE 2:1)	137 yd3
Body	59,625 lb
Chassis	225,500 lb
Gross Weight - Empty	310,525 lb

Source

More in Cat: 789, 785 Bare Chassis, 793C.