Steering & Braking Systems
Differential steering, articulated steering, priority valves, metering sections, parking brakes, and brake valve diagnostics.
- Explain differential steering operation in tracked machines
- Describe articulated steering systems and priority valve function
- Identify metering section types and their applications
- Explain spring-applied, hydraulic-released (SAHR) parking brake operation
- Diagnose common steering and braking system faults
Leçon 1
Steering System Types & Differential Steering
Steering in Heavy Equipment
Heavy equipment uses different steering systems depending on machine type and application. Tracked machines use differential steering, while wheeled machines use articulated or conventional steering. Understanding each system is essential for proper diagnosis and repair.
Differential Steering
Tracked machines - dozers, excavators
Slows or stops one track to turn
Uses clutch and brake on each side
Tight turning radius possible
Articulated Steering
Wheeled machines - loaders, haul trucks
Frame pivots at center joint
Hydraulic cylinders push frame halves
Equal tire wear on all axles
Differential Steering Operation
In a differential steering system, each track is driven independently. To turn, the system slows or stops the track on the inside of the turn while the outside track continues at full speed. Modern systems use hydrostatic motors for each track, allowing smooth speed control and counter-rotation (pivot turns) where one track drives forward and the other reverses.
Clutch-and-Brake Steering
Older tracked machines use clutch-and-brake steering. Disengaging the steering clutch on one side disconnects that track from the drivetrain, allowing the machine to drift in that direction. Applying the steering brake on that side forces a tighter turn. This system is simpler but provides less precise control than hydrostatic steering.
Exam Tip - Steering Drift
If a tracked machine drifts to one side, the most likely cause is a worn or slipping steering clutch on the opposite side, or unequal track tension between the two sides.
Differential steering turns tracked machines by varying the speed of each track independently. Clutch-and-brake steering disconnects and brakes one track to turn. Modern systems use hydrostatic motors for smoother, more precise steering control.