Suspension & Steering Flashcards
7 cards from real LEC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Suspension & Steering flashcards as text
What is the primary purpose of anti-roll bars (stabilizer bars) on some locomotive truck designs?
Answer: To limit excessive body roll while still allowing independent vertical wheel movement
Anti-roll bars resist body roll by linking left and right suspension sides torsionally, improving stability without stiffening the vertical ride.
A locomotive is found to have a negative wheel load (wheel lifting) on one corner during curve negotiation. What is the most dangerous consequence?
Answer: Potential derailment due to unloaded wheel climbing the rail
A wheel with near-zero or negative vertical load loses its resistance to flange climb, dramatically increasing the risk of derailment.
Which FRA track class allows the highest maximum speed for freight locomotives, and how does suspension design relate to this?
Answer: Class 5 at 80 mph — suspension must handle higher dynamic forces at speed
FRA Class 5 permits freight operations up to 80 mph, requiring suspension systems engineered to manage the greater dynamic loads and stability demands at those speeds.
What does 'flange wear' indicate about a locomotive's steering performance?
Answer: Excessive lateral forces, often from misaligned trucks or tight curves
Accelerated flange wear signals that the wheelset is repeatedly forced against the rail flange, indicating misalignment, worn suspension, or excessive curving forces.
In a three-piece truck (side frames + bolster), what provides lateral restraint to the bolster?
Answer: Friction between bolster ends and side frame columns, plus bolster guides
Bolster guides on the side frame columns and friction surfaces at the bolster ends collectively restrain lateral bolster movement while allowing vertical travel.
Which locomotive inspection standard requires checking suspension components for cracks, worn wedges, and spring condition?
Answer: FRA 49 CFR Part 229 (Railroad Locomotive Safety Standards)
FRA 49 CFR Part 229 governs locomotive safety standards, including required inspection of suspension components such as springs, wedges, and structural members.
What effect does increasing the secondary suspension spring rate have on ride quality?
Answer: Stiffer ride — more track irregularities are transmitted to the carbody
A higher (stiffer) spring rate transmits more of the track input force to the carbody, resulting in a harsher ride.