Examkin

Question

Difficulty: HardSpecialty Fasteners and Anchors

During the overhaul of a heavy-duty vehicle steering and suspension linkage, a technician must secure a tapered ball joint stud exposed to severe cyclic vibration. Specification guidelines strictly prohibit friction-only retention methods such as lock washers or nylon inserts because rotational back-off could cause total loss of steering control. Which specialty fastener combination provides positive mechanical locking by seating across radial crown slots and passing through a drilled cross-hole in the fastener shank?

  1. A
    Grade 8 high-tensile hex cap screw paired with a hardened steel washer
  2. B
    Metric prevailing-torque all-metal locknut tightened to proof load
  3. Slotted castle nut secured with a steel cotter pinAnswer
  4. D
    Tapered spring retention seat fitted with a rubber compression isolator

Answer

Slotted castle nut secured with a steel cotter pin
The slotted castle nut paired with a steel cotter pin provides positive mechanical retention. The cotter pin passes through the crown slots of the nut and the transverse hole in the stud shank, mechanically blocking the nut from turning even if tension is reduced.

Step-by-Step Solution

1
Analyze the mechanical constraint and application requirements
The application requires positive mechanical retention where fastener rotation is physically blocked, rather than relying on thread friction or washer spring tension.
Severe dynamic vibration in critical automotive steering linkages can overcome friction-based locking devices, leading to dangerous detachment.
2
Evaluate the geometric design of the specialty fastener
A castle nut features machined radial slots (crenellations) on its crown that align with a transverse hole drilled through the threaded bolt shank.
Aligning the slots with the cross-hole creates a continuous channel across the fastener interface.
3
Identify the retaining locking element
Inserting and bending the prongs of a steel cotter pin through the slots and cross-hole creates a physical barrier to rotational movement.
The pin must physically shear before the nut can rotate, providing true positive locking independent of bolt clamp load.

Key Concept

Positive mechanical locking using slotted castle nuts and cotter pins in high-vibration applications
Estimated Time:1m 30s
Rate this question

Topics

Specialty Fasteners and Anchors

More questions from this topic