Examkin

Automotive Chassis and Drivetrain

144 questions

All types144Multiple choice74Matching35Ordering35
Question 141Question →

In an automatic transmission's simple planetary gearset, the planet pinion carrier is held stationary while the central sun gear is driven as the input member. Under these operating conditions, what mechanical output is produced at the outer ring gear?

Show answer & explanation

Answer: It rotates in the opposite direction of the sun gear at a reduced rotational speed.

Answer

The ring gear rotates in the opposite direction of the sun gear at a reduced rotational speed, providing reverse gear reduction.
When the planet carrier is held stationary by a band or clutch and the sun gear is driven, the planet pinions rotate on fixed shafts like standard idler gears. This external mesh reverses the direction of rotation when transferring drive to the internally toothed ring gear. Because the ring gear has significantly more teeth than the sun gear, the ring gear turns at a lower rotational speed with multiplied torque, creating reverse reduction.

Step-by-Step Solution

1
Analyze the stationary reaction member
The planet pinion carrier is held stationary relative to the transmission case.
Holding the carrier locks the centers of the planet pinions in fixed positions in space.
2
Determine the direction of rotation
The planet pinions act as stationary idler gears, rotating in the opposite direction of the sun gear and driving the internal teeth of the ring gear in that same reversed direction.
External gear mesh between the sun gear and planet pinions reverses rotational direction.
3
Evaluate the gear ratio and speed relationship
Output speed at the ring gear is reduced because the ring gear has more teeth than the input sun gear.
The gear ratio is determined by the ratio of ring gear teeth to sun gear teeth (−NsunNring-\frac{N_{sun}}{N_{ring}}), yielding a reverse gear reduction.

Key Concept

Planetary gearset kinematics and reverse gear operation in automatic transmissions
Estimated Time:1m 0s
Question 142Question →

Match each automotive clutch or transmission component with its primary mechanical or hydraulic function.

Click a left item, then click its matching right item

Items

Torque converter stator
Clutch pressure plate
Manual transmission shift fork
Automatic transmission valve body

Matches

Show answer & explanation

Answer

Torque converter stator matches redirecting fluid to multiply torque; Clutch pressure plate matches clamping the friction disc against the flywheel; Manual transmission shift fork matches sliding the synchronizer sleeve to engage a selected gear; Automatic transmission valve body matches directing pressurized fluid to actuate clutches and bands.
Each drivetrain component matches its specific mechanical or hydraulic operation: the torque converter stator redirects fluid back to the impeller for torque multiplication, the pressure plate applies spring force to clamp the clutch disc, the shift fork moves the synchronizer sleeve along the shaft, and the valve body routes pressurized fluid to control automatic shifts.

Step-by-Step Solution

1
Identify the primary role of the torque converter stator in fluid coupling.
The stator redirects fluid coming off the turbine to spin in the same direction as the impeller, multiplying torque at low vehicle speeds.
Without the stator redirecting fluid, the returning fluid would counteract the impeller rather than boost its rotational efficiency.
2
Identify the primary clamping component of a manual clutch assembly.
The pressure plate provides the high normal force required to bind the friction disc against the engine flywheel.
Frictional coupling between the flywheel, disc, and pressure plate is what transfers power into the gearbox when the clutch pedal is released.
3
Determine the selector linkage mechanism in a manual gearbox.
The shift fork bridges driver movement from the shift rail to the synchronizer sleeve.
Sliding the sleeve engages the clutching teeth on the speed gear after speeds are equalized.
4
Analyze the role of the hydraulic control center in an automatic transmission.
The valve body distributes pressurized transmission fluid to apply bands and multiple-disc clutch packs.
Planetary gearsets require specific hydraulic holding mechanisms to establish different gear ratios.

Key Concept

Operational principles and component functions of manual clutches, manual gearboxes, torque converters, and automatic transmission hydraulic controls.
Estimated Time:1m 0s
Question 143Question →

In a constant-mesh manual transmission, what is the primary function of the synchronizer blocker ring during a gear shift?

Show answer & explanation

Answer: It uses frictional contact to match the rotational speed of the selected gear to the transmission shaft before engagement.

Answer

The synchronizer blocker ring uses frictional contact to match the rotational speed of the selected gear to the transmission shaft before engagement.
In a manual transmission, the synchronizer blocker ring acts as a miniature cone clutch. When a driver selects a gear, the shift sleeve forces the blocker ring against the tapered cone of the freewheeling gear, using friction to rapidly match its rotational speed with the mainshaft so the locking sleeve can engage without grinding.

Step-by-Step Solution

1
Identify the role of the synchronizer assembly in a manual transmission
Recognize that constant-mesh gears rotate at different speeds on the output shaft until locked to the shaft by a synchronizer sleeve.
Shifting gears directly without speed matching would cause severe clashing and grinding of the engagement teeth.
2
Analyze the mechanical interaction of the blocker ring
As the shift fork moves the synchronizer sleeve toward the selected gear, the sleeve pushes the blocker ring against the tapered cone surface of the gear.
The frictional drag generated between the blocker ring cone and the gear cone brings both components to identical rotational speeds.
3
Determine the completion of the shift
Once speeds are equalized, the blocker ring aligns its external dog teeth, allowing the sliding sleeve to smoothly lock onto the gear.
Speed synchronization must occur prior to mechanical engagement to prevent component damage.

Key Concept

Manual Transmission Synchronizer Operation and Speed Equalization
Estimated Time:1m 0s
Question 144Question →

In an automotive automatic transmission, hydrodynamic fluid coupling within the torque converter transfers rotational power from the internal combustion engine to the transmission gearbox. In what sequential order does fluid and mechanical force transfer power through the torque converter components during acceleration?

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct sequence begins with the engine spinning the flexplate and converter housing, followed by centrifugal fluid acceleration from the impeller, fluid impact rotating the turbine, fluid redirection through the central stator to multiply torque, and final delivery of rotational force to the transmission input shaft via the splined turbine hub.
Power transfer through a torque converter starts mechanically at the flexplate, which spins the outer housing and impeller pump. The impeller slings automatic transmission fluid outward via centrifugal force into the turbine vanes, driving the turbine. Returning fluid from the turbine is redirected by the stator back toward the impeller to multiply torque, and the spinning turbine transfers output torque directly into the splined transmission input shaft.

Step-by-Step Solution

1
Identify the primary mechanical input from the engine to the converter.
The crankshaft rotates the flexplate, which directly drives the torque converter outer housing and integral impeller pump.
The torque converter housing is bolted directly to the flexplate, ensuring the impeller turns at engine speed.
2
Determine how the spinning impeller acts upon the transmission fluid.
Centrifugal force pushes hydraulic fluid outward across the impeller vanes at high velocity.
The impeller functions as a pump that converts rotational mechanical energy into fluid kinetic energy.
3
Trace the path of the discharged fluid to the driven member.
Pressurized fluid strikes the outer perimeter of the turbine vanes, causing the turbine to rotate.
Hydrodynamic force from the moving fluid transfers torque across the fluid coupling to the turbine.
4
Follow the fluid path through the central reaction component.
Fluid flowing out of the turbine passes through the stator blades, which redirect the flow into the impeller's rotation direction.
Redirecting fluid to assist the impeller rather than opposing it creates torque multiplication during vehicle acceleration.
5
Identify the final mechanical output entering the transmission gearbox.
The turbine's splined hub drives the transmission input shaft.
The turbine is mechanically coupled via splines to the transmission input shaft to power downstream planetary gearsets.

Key Concept

Hydrodynamic torque converter power flow and torque multiplication
Estimated Time:1m 15s
PreviousPage 8 / 8
Automotive Chassis and Drivetrain Practice Questions — Armed Services Vocational Aptitude Battery (ASVAB) — Page 8 | Examkin