Mechanical Power Train
The Cat mechanical drive power train and power shift transmission provides unmatched operating efficiency and control on steep grades, in poor underfoot conditions, and on haul roads with high rolling resistance.
Transmission
Pairing the Caterpillar seven-speed planetary power shift transmission with the C18 diesel engine with ACERT Technology delivers constant power over a wide range of operating speeds.
• Transmission Chassis Control (TCC)
Transmission shifting is based on Transmission Output Speed for optimum performance efficiency and clutch life. The TCC provides integrated functionality to controlled throttle shifting, directional shift management, neutral coast inhibitor, body-up shift limiter and body-up reverse neutralizer.
Throttle Lock
The operator can now electronically lock the throttle pedal at full throttle, to reduce fatigue on long uphill hauls. The throttle can be locked on by momentarily depressing the throttle lock switch located on the operator console, while depressing the pedal fully. The throttle is released whenever braking is applied or the throttle is again depressed.
Lock-Up Torque Converter
Combines maximum rimpull and cushioned shifting of torque converter drive with the efficiency and performance of direct drive. The torque converter includes: an additional clutch plate to maintain power train capability for higher horsepower and top speed, a new torque converter adapter that provides extra length to house the additional clutch plate and enables the converter components to be changed without having to change the housing, and a new sump oil level switch that serves as an emergency warning if oil is lost. The lock-up torque converter engages at approximately 8 km/h (5 mph), delivering more power to the wheels.
Lock-Up Clutch
Quickly releases and re-engages to reduce power train torque loads for smoother shifting, long life and a more comfortable ride.
New Differential and Proven Final Drives
The new Cat differential works with the proven final drives as a system to deliver maximum power to the ground. For improved serviceability, the pinion gear is cantilever mounted, which allows inspection of the differential without pulling the rear-end. Visual inspection of the pinion gear and bearings can be performed in 1-2 hours versus 8 hours on the previous models. In addition, the differential bevel pinion gear set is designed for improved adjustability, which results in improved contact patterns and life. The differential gear set also provides enhanced bending life for steeper grade applications.
New Differential Center Housing
A new, ductile iron center housing improves quality and reliability. The improved stiffness allows for better main support bearing life. The new housing also uses bolts, reducing maintenance time. This change also improves wheel station bolted-joint life.
New A-Frame
The new A-frame mounts directly to the spindles. The new A-frame eliminates the “king” bolt and includes a pin and bushing style mounting, consistent with the 777 and 793. This new design is simpler to maintain and service.
New Ductile Iron Spindles
A stress-optimized, ductile iron spindle is splined to the rear brakes, reducing brake pack rebuild time by up to two hours. In addition, the spindles are longer and wider with fewer seals for increased strength and durability.
Mechanical Power Train
The Cat mechanical drive power train and power shift transmission provides unmatched operating efficiency and control on steep grades, in poor underfoot conditions, and on haul roads with high rolling resistance.
Transmission
Pairing the Caterpillar seven-speed planetary power shift transmission with the C18 diesel engine with ACERT Technology delivers constant power over a wide range of operating speeds.
• Transmission Chassis Control (TCC)
Transmission shifting is based on Transmission Output Speed for optimum performance efficiency and clutch life. The TCC provides integrated functionality to controlled throttle shifting, directional shift management, neutral coast inhibitor, body-up shift limiter and body-up reverse neutralizer.
Throttle Lock
The operator can now electronically lock the throttle pedal at full throttle, to reduce fatigue on long uphill hauls. The throttle can be locked on by momentarily depressing the throttle lock switch located on the operator console, while depressing the pedal fully. The throttle is released whenever braking is applied or the throttle is again depressed.
Lock-Up Torque Converter
Combines maximum rimpull and cushioned shifting of torque converter drive with the efficiency and performance of direct drive. The torque converter includes: an additional clutch plate to maintain power train capability for higher horsepower and top speed, a new torque converter adapter that provides extra length to house the additional clutch plate and enables the converter components to be changed without having to change the housing, and a new sump oil level switch that serves as an emergency warning if oil is lost. The lock-up torque converter engages at approximately 8 km/h (5 mph), delivering more power to the wheels.
Lock-Up Clutch
Quickly releases and re-engages to reduce power train torque loads for smoother shifting, long life and a more comfortable ride.
New Differential and Proven Final Drives
The new Cat differential works with the proven final drives as a system to deliver maximum power to the ground. For improved serviceability, the pinion gear is cantilever mounted, which allows inspection of the differential without pulling the rear-end. Visual inspection of the pinion gear and bearings can be performed in 1-2 hours versus 8 hours on the previous models. In addition, the differential bevel pinion gear set is designed for improved adjustability, which results in improved contact patterns and life. The differential gear set also provides enhanced bending life for steeper grade applications.
New Differential Center Housing
A new, ductile iron center housing improves quality and reliability. The improved stiffness allows for better main support bearing life. The new housing also uses bolts, reducing maintenance time. This change also improves wheel station bolted-joint life.
New A-Frame
The new A-frame mounts directly to the spindles. The new A-frame eliminates the “king” bolt and includes a pin and bushing style mounting, consistent with the 777 and 793. This new design is simpler to maintain and service.
New Ductile Iron Spindles
A stress-optimized, ductile iron spindle is splined to the rear brakes, reducing brake pack rebuild time by up to two hours. In addition, the spindles are longer and wider with fewer seals for increased strength and durability.
Box-Section Design
The 772 frame uses a box-section design, incorporating two forgings and 13 castings in high-stress areas with deep penetrating and continuous wrap-around welds to resist damage from twisting loads without adding extra weight.
• Steel Structures
Mild steel used throughout the frame provides flexibility, durability and resistance to impact loads, even in cold climates and allows for easy field repairs.
• Castings
Castings have large radii with internal reinforcing ribs to dissipate stress in areas of high stress concentration. Castings move welds to lower stress areas for greater frame life.
Integral Four-Post ROPS Cab
Resiliently mounted to the main frame with all-new cab mounts that reduce vibration and sound, the integral ROPS is designed as an extension of the truck frame. The ROPS/FOPS structure provides “five-sided protection” for the operator.
Forgings and Castings
- The 772 features a drop tube/casting design and two forged steel mountings for hoist cylinders, similar to the design as found on the 775.
- A volcano casting that holds the center tube is enhanced with thicker wall dimensions for increased durability.
- New strut-mount castings have been moved 10 in (254 mm) forward and 1 in (25.4 mm) outward on each side. These thicker strut-mount castings and their location improve ride characteristics as well as durability.
- New steering casting (same as 775) accommodates larger steering cylinders and ball studs.
- New tail casting accommodates new angled rail design.
Superior Weld Quality
Structural frame welds are J-groove type, ensuring full weld penetration for strength and longevity. During fabrication, weld integrity is further enhanced by rotating the frames 360 degrees to provide optimal, flat welding surfaces.
Technology Enhanced
Caterpillar structures are tested using System Structural Analysis (SSA) to dynamically simulate operations in field environments and identify potential structural improvements in high stress areas. With analysis of machine structures and variables, such as haul road and payload, structural improvements were made to the frame to accommodate the new cab, platform, engine and radiator.
Quality Control
A Coordinate Measuring Machine (CMM) is used to inspect truck frames for consistency in the manufacturing process. In addition all critical welds receive testing to verify weld penetration which results in frame durability.
All New Center-Mounted Cab
Center cab positioning provides additional room and creates a walk-in-style cab. The new configuration allows the operator to easily enter and exit the cab. The cab environment offers a spacious surrounding, giving the operator the ability to stretch out and providing superior comfort for an entire operating shift. The operator seat is located on the right hand side of the cab with the trainer to the immediate left.
Ergonomic Layout
The 772 operator’s station is ergonomically designed for total machine control in a comfortable, productive and safe environment. All controls, levers, switches and gauges are positioned to maximize productivity and minimize operator fatigue.
New ISO Designed Cab Mounts
Integral, sound-suppressed cab is resiliently mounted to the frame to isolate the operator from sound and vibration for a quiet, secure and comfortable ride.
Viewing Area
Designed for excellent all-around visibility and clear sight lines to the haul road. The large viewing area, with 52 percent more glass, enables the operator to maneuver with confidence for greater productivity.
Cat Data Link
Electronically integrates machine computer systems to optimize overall power train performance, increase reliability and component life, and reduce operating costs. All the information from these controls can be accessed through a laptop computer with Cat ET.
Transmission Chassis Control (TCC)
TCC uses electronically transferred engine rpm data to execute shifts at preset points for optimum performance, efficiency and clutch life.
Electronic Technician (Cat ET)
Cat ET service tool provides service technicians with easy access to stored diagnostic data through the Cat Data Link to simplify problem diagnosis and increase machine availability. Cat ET is beneficial because of how it displays the status of all engine parameters, including throttle position, timing and fuel flow. Critical data from the electronic engine and transmission controls, including transmission shifting, engine speed and fuel consumption, provides service technicians with enhanced diagnostic capability to reduce downtime and operating costs.
Controlled Throttle Shifting
Regulates engine rpm during shifting to reduce power train stress and clutch wear by controlling engine speed, torque converter lock-up and transmission clutch engagement for smoother shifts and longer component life.
Directional Shift Management
Regulates engine speed during directional shifts to prevent damage caused by high-speed directional changes.
Full Hydraulic Service Brake
The 772 features a full hydraulic brake system, which offers significant improvements in reliability, response, control and serviceability versus an air-over hydraulic system. There are fewer components (part by part comparison), boosting reliability and streamlining maintenance.
Hydraulic Accumulators
The brake system is equipped with a primary accumulator and a secondary accumulator, which also provides back-up braking in the event of a failure. The accumulators automatically drain pressure after shutdown, reducing the service time by removing the need to drain the pressure off the system and reducing the risk of high-pressure exposure during maintenance. The new brake system uses a pump that is driven off the flywheel 100 percent of the time and is only loaded when hydraulic pressure falls below 1,600 psi. The pump will cut out at 1,975 psi. In the new system, oil in this circuit is also sent to the hydraulic fan system. Any additional oil is sent to the brake cooling system along with the oil used in the drive fan.
Improved Reliability
Because oil is now used to actuate the brakes, Caterpillar has eliminated the need for two brake master cylinders, two relay valves, an air dryer and the retarder valve (found on ARC trucks only) that were associated with the air-over-hydraulic brake system. The air system had complexity, which affected its reliability. The oil actuated system is simpler and more reliable.
Extended Life Multiple Disc Brakes (optional)
Extended life friction material has double the wear life of standard brakes and is twice as resistant to glazing for more consistent braking power with less noise.
Brake Design
Cat rear oil-cooled disc brakes are designed with large discs and plates for reliable, adjustment-free operation and performance. Rear brakes are completely enclosed and sealed to prevent contamination and reduce maintenance.
