FUN 101 Week 3 Hardware Review

Technicians A and B were discussing the size and type of cap screws to use to attach a PTO mounting bracket to a cast iron transmission case. Technician A says that fine-threaded cap screws should be used because they have stronger threads than coarse-threaded ones. Technician B says coarse-threaded fastener threads should be used in soft cast material. Who is correct?

Technicians A and B were discussing which grade of bolts to use to attach a pintle tow hook to a tractor frame. Technician A says that Metric class 10.9 would be acceptable. Technician B says that Grade 8s are required. Who is correct?

After taking over a brake job from another technician, Technicians A and B found a box of wheel studs and nuts with both right- and left-hand threads. Technician A said that the left-hand threaded fasteners should be installed on the left-side wheels. Technician B said the left-handed threads should go on the right side to prevent a wheel separation. Who is correct?

Technician A said that a class 9 nut should not be matched with a class 9.8 bolt because its threads are not as strong as the bolt. Technician B said that a softer nut strength will help prevent threads from pulling or stripping when tightened. Who is correct?

Technician A says that lubricating fastener threads enables more rotational force to convert to preload and clamping force. Technician B says that zinc-plated fasteners do not require lubrication to reduce thread resistance. Who is correct?

Technician A says that a fastener that’s tightened even a small amount above its maximum torque is more likely to break than one properly tightened. Technician B says that a fastener that is under tightened is much more likely to break than one that’s tightened slightly too much. Who is correct?

Technician A says that tightening a fastener using a torque wrench is the most accurate method to ensure preload tension on a fastener is correct. Technician B says that thread friction can cause wide variations in preload tension after tightening a fastener. Who is correct?

Technician A says that using prevailing torque flange nuts and flange bolts are the best fasteners to use on truck frames. Technician B says that SAE grade 8 or class 9.8 M series fasteners with flat washers and lock washers are just as effective. Who is correct?

Technician A says that to repair stripped threads in a bell housing used to attach a transmission, it is best to drill out the damaged thread and install a larger diameter fastener after tapping new threads. Technician B says that the thickness of the bell housing face is too narrow to drill and install an oversize fastener, and the hole threads should be welded and tapped instead. Who is correct?

Technician A says that a taper tap is used to cut new threads in a blind hole. Technician B says that a bottoming tap is needed to cut threads to the bottom of the hole. Who is correct?