Light-Duty Drive Axle Assemblies

What is the primary function of drive axle gear sets, regardless of whether they are used in a transaxle, RWD, AWD, or 4WD vehicle?

To ensure both drive wheels turn at the same speed while cornering. To prevent the drive axle assembly from ballooning due to pressure changes. To provide a final gear reduction resulting in a torque increase and a speed decrease. To always change the direction of power flow by 90 ° .

In rear-wheel drive (RWD) and four-wheel drive (4WD) drive axle assemblies, which type of gear set is most commonly used for the ring gear and drive pinion?

Helical gears Bevelled spur gears Hypoid gears Amboid gears

The design of a hypoid gear set allows the driveshaft to be lowered, thereby lowering the overall vehicle profile. This is achieved because the drive pinion shaft centerline is located:

In the same plane as the ring gear centerline. Above the ring gear centerline (Amboid design). Below the ring gear centerline. At a 90 ° angle to the output rotation.

What is the consequence of the large curvature of the gear teeth in a hypoid gear set?

It eliminates the need for lubrication. It allows the gear set to operate quietly with zero side thrust. It causes a great deal of side thrust. It allows the gear teeth to be fully engaged at all times.

Which gear type, shaped like truncated cones for strength, is characterized by producing thrust as the gears want to separate when torque is applied, making them suitable for use in the differential assembly?

Helical gears Straight-cut bevel gears Hypoid gears Spur gears

What gear type is typically used in the differential unit as the differential pinion gears and axle or side gears?

Hypoid gears Straight-cut bevel gears Bevelled spur gears Double offset joints

The primary reason bevelled spur gears (used in the differential) are considered a relatively weak gear set is that:

They produce excessive side thrust. They are only used in non-traction-enhancing differentials. Only one tooth of a spur gear set is fully engaged at a time, resulting in a small load contact area. They are made of soft, stamped steel that is not induction hardened.

In a transverse-mounted transaxle assembly, which uses helical drive axle gears, what is the required change in the path of power?

The path of power must turn 90 ° from the input. The path of power must be parallel to the differential case. The path of power does not always turn 90 ° . The output rotation must be above the centerline of the ring gear.

Drive axle gear sets transfer power between two shafts whose centrelines are parallel. What is the most common type of gear used for this application, particularly in front-wheel drive vehicles?

Hypoid gears Bevel gears Helical gears Bevelled spur gears

What is the mathematical method used to calculate the gear ratio of the crown and pinion set?

Dividing the number of teeth on the pinion by the number of teeth on the ring gear. Multiplying the ring gear diameter by the pinion gear diameter. Dividing the number of teeth on the ring by the number of teeth on the pinion gear. Counting the total number of gear sets in the axle assembly.

Which axle type is most common in rear-wheel drive passenger vehicles and supports the weight of the vehicle while propelling the wheel?

Full floating axle Independent (swing axle) Semi-floating axle Removable carrier axle housing

A full floating axle is commonly found on 3/4-ton and heavier vehicles. Which function is solely performed by the axle shaft in this design?

Supporting the vehicle weight. Transferring side thrust. Supporting the outer end with a wheel bearing. Transferring torque between the wheels and the driveline.

In a semi-floating axle that uses straight roller bearings to support the axle shaft, how is the required side thrust control transferred to the axle housing?

The outer bearing retainer plate absorbs the thrust directly. A C-lock on the end of each axle allows the axle shaft to press against the differential pinion shaft, which transfers thrust to the differential case side bearings. The inner end of the axle shaft is supported by a pilot bearing inside the differential case. The differential side gear transfers thrust directly to the axle housing via shims.

To service an axle in an integral carrier axle housing, which procedure must be performed first?

Remove the companion flange. Remove the differential carrier. Remove the rear cover. Remove the axle shaft locking clip.

What distinguishes the integral carrier axle housing from the removable carrier (banjo type) axle housing?

The integral carrier uses steel axle tubes, while the removable carrier uses cast iron tubes. The integral carrier has a removable cover opposite the companion flange, while the removable carrier does not have a removable cover. The integral carrier is used on 3/4-ton and larger trucks only. The integral carrier uses coil springs, while the removable carrier uses leaf springs.

What critical adjustment is controlled by the side-to-side position of the differential case, which is set using selective shims or threaded adjusters?

Pinion depth Pinion bearing preload Backlash between the drive pinion and the ring gear. Differential gear ratio.

To maintain proper preload on drive pinion tapered roller bearings, many manufacturers utilize a crush sleeve positioned between the bearings. What is the mandatory replacement rule concerning this component?

It must be lubricated with high-viscosity gear oil upon removal. It must be replaced only if it shows scoring or galling. Once a crush sleeve has been used, it cannot be reused. It must be shimmed precisely to match the bearing race diameter.

What is the fundamental requirement for bevel gears used in the differential, such as bevelled spur gears, regarding the shafts they connect?

They must provide a very large torque multiplication. They must be used where the shafts are parallel. The gears must rotate at 90 ° to each other. They must eliminate all end thrust.

In a standard differential, when a vehicle is driving in a straight line, what is the state of the gear rotation?

The pinion gears rotate on their shaft to divide torque. The differential case speed is greater than the wheel speed. Everything (ring gear, differential case, pinion gears, axle gears, and wheels) turns at the same speed. The outside wheel rotates 110% faster than the inner wheel.

When a vehicle with a standard differential is rounding a corner, what occurs regarding the speed of the wheels relative to the differential case?

The inside wheel speeds up, and the outside wheel slows down. The inside wheel slows down, and the outside wheel speeds up. Both wheels speed up to match the ring gear speed. The differential case speed increases to equal the average of the two wheel speeds.

What component of the standard differential ensures that torque is divided equally between both drive wheels?

The ring gear The differential case The differential pinion gears The axle shafts

A standard differential always splits the torque equally between the two driving wheels. If one wheel is on a slippery surface (ice), what is the maximum torque that can be delivered to the wheel with traction?

The torque required to overcome friction at the wheel with traction. Double the torque required to overcome traction at the wheel on the ice. The torque required to overcome traction at the wheel on the ice. The maximum available engine torque.

Traction-enhancing differentials are classified into two main categories: those that limit differential action and those that eliminate differential action completely. Which category is achieved by mechanically locking the two axles together?

Friction designs Locking differentials Viscous coupling differentials Limited slip differentials

A differential with four differential pinion gears instead of the standard two is used to provide what specific performance characteristic?

Better traction on slippery surfaces. Greater torque multiplication. Increased load capacity by dividing the torque between four gears, reducing the load on each pinion gear. More gear reduction for high-speed operation.

Disc Clutch Differentials (Limited Slip, Posi-Trac, etc.) use friction plates (clutch packs) that are stacked alternately between internally splined plates (engaging the side gear) and externally splined plates (engaging the differential case). When loss of traction occurs, what happens?

The clutch pack disengages, allowing the wheel with traction to spin. The internal splines sheer, locking the two axle gears together. The clutch pack is placed under compression, causing the side gear to be driven by the case through the clutch pack in addition to the normal path of power. The pinion gears stop rotating entirely, transferring power directly to the axle.

In a disc clutch differential, what components supply the spring tension necessary to compress the clutch packs, thereby creating the clutch preload?

Axial loads generated by the wheel bearings. Coil type pre-load springs, wave springs, dished plates (Belleville spring), or wave plates. The friction discs and steel plates themselves. The torque required to slip the clutches.

Traction-enhancing differentials utilize the natural tendency of bevelled spur gears to thrust one another apart under load. This thrust is transferred to the axle side gear and used to provide what function?

Additional compression on the clutch packs behind the axle gears. Torsional dampening to prevent wheel hop. Lubrication spaces between the shaft and the pinion gears. Constant velocity when operating at high angles.

The multi-disc limited slip differential does not permanently lock the differential case and axle side gears. What condition allows normal differential action (slippage) to occur when turning a corner?

The pinion gears stop rotating on their shaft. The spring tension exerted by the pre-load springs can be overcome. The differential governor activates the locking feature. The side thrust is eliminated by the thrust washers.

If a vehicle is equipped with a limited slip differential (LSD) assembly, what maintenance additive is generally required and may be contained in a special lubricant or supplied separately?

Extreme-pressure (EP) additive. Anti-foaming agent. Friction modifier. Seal compatibility additive.

Cone Clutch Differentials operate on the same principle as disc clutch types, but instead use cone clutches placed between the side gears and the differential case. What feature on the cone’s machined surface is designed to cut through the lubrication film and bite into the differential case?

Axial splines Internal threads A spiral groove or milled slots. A smooth, heat-treated surface.

In a Viscous Coupling Differential (popular in AWD and SUV applications), torque transfer occurs due to the use of viscous silicone oil and multiple perforated plates. What property of the silicone oil causes it to become more adhesive and resistant to flow?

High oxidation resistance. It is heated through agitation (shearing). Low temperature mobility. Resistance to foaming.

The Eaton Locking Clutch Differential is distinct because there is almost no discernible drag until the locking feature is activated by what mechanism?

The friction discs slipping excessively. The governor engages. The operator twists one axle shaft in the opposite direction. The air shift cylinder is actuated.

How does a technician typically confirm that a differential is a traction-enhancing type (rather than a standard differential) without dismantling it?

Drive the vehicle slowly around a corner and listen for gear clash. Raise the vehicle, put the transmission in neutral, and if turning one wheel causes the opposite wheel to turn in the same direction, it is safe to assume it is traction-enhancing. Check for excessive backlash between the ring and pinion. Measure the side thrust tolerance on the axle shaft.

Locking differentials eliminate differential action completely by mechanically locking the two axles together. When is this locking action typically initiated in an Eaton Locker type differential?

Immediately when the clutch is disengaged. When the operator sharply twists one axle shaft in either direction, causing the governor to engage with a solid clunk. When the vehicle is placed into deep reduction gear. When the temperature of the gear oil exceeds 90 ° C.

The term preload (in the context of tapered roller bearings) is defined as the pressure required to make the bearing and the race contact each other, causing the rollers to rotate. What is the explicit purpose of this preload?

To lubricate the bearing surfaces. To prevent any axial movement. To increase the gear ratio. To reduce the need for thrust washers.

What is the classification of gear oil that is recommended for use with hypoid gear sets?

SAE 75W GL-1 API GL-5 SAE 140

What is the specific role of an extreme-pressure (EP) additive like zinc dithiophosphate in drive axle gear oil?

To minimize foaming during high-speed rotation. To maintain viscosity over a wide temperature range. To adhere to gear surfaces and prevent metal-to-metal contact under high torque conditions. To improve oil flow when the differential is cold.

Which of the following is a potential consequence if the drive axle breather vent is not kept unrestricted?

Gear oil viscosity will break down rapidly. The clutch preload will increase. Fluid leaks from any of the axle housing seals (due to excess pressure). The driveshaft will speed up and slow down (variable velocity).

Drive axle gear oil must be checked against the manufacturer's specifications for two major classifications: SAE (viscosity) and API (application). Why must a customer always check manufacturer specifications before adding any fluid?

To ensure the fluid can resist mechanical linkage wear. To ensure the fluid has a high enough GL number for all applications. Mixing different types of gear oil causes a breakdown chemically. To confirm the axle housing has a dedicated oil pump.

How does the splash lubrication system commonly used in remote axle assemblies ensure internal components are lubricated?

The transaxle dipstick checks the oil level in the common sump. The ring gear and differential case turn, drawing oil out of the sump and throwing it up and forward against the top of the axle housing. Helical gears transfer oil between two shafts with parallel centrelines. A dedicated low-pressure pump directs oil through channels in the case.

In a transversely mounted transaxle using helical drive axle gears, how do the demands on the lubricating oil compare to those of a rear axle assembly using hypoid gear sets?

The demands on the oil are equally high due to axial thrust. The demands on the oil are not as high. Helical gear sets always require ATF fluid, which has higher demands. Transaxles require a high GL number gear oil.

What is the primary method for identifying the specific drive axle assembly when providing replacement crown and pinions?

Matching the ratio (e.g., 3.50) stamped on the axle tube. Measuring the diameter of the crown gear. Decoding the axle assembly identification number (stamping codes or metal tag). Identifying the type of carrier (integral or removable).

Axle shafts are manufactured with splines machined at the inner end. What is the purpose of these splines?

To accommodate C-locks for side thrust control. To allow the shaft to be pressed onto a retainer ring. To engage the differential side gears for power transmission to the wheels. To support the vehicle weight (radial loads).

Axial loads are defined as loads that run parallel to the centerline of the shaft. Which type of bearing is normally used in most drive axle applications because it can accept and control both radial and axial loads?

Straight roller bearings Ball bearings Tapered roller bearings Spherical roller bearings

When a differential is subjected to the spinning of one wheel (such as when stuck), severe wear can occur to the differential pinion gears. This is because:

They are made of bevelled spur gears, a relatively weak set. Under normal driving conditions, they do not turn at high speed on the differential pinion shaft, but high-speed turning occurs when one wheel spins. They are always preloaded with heavy springs, increasing friction. They are locked to the differential case via the side gear thrust washers.

When a differential case fails, what essential components are suggested as related sales, according to Table 2?

Bearings, gasket and seals, differential cross-shaft, differential gears, shims, crush sleeve, gasket, and gear lube. Only the crown and pinion set. Only the axle tube vent and hose. Side gears and axle shaft flanges.

When a semi-floating axle uses a ball bearing type for support, how are the side thrust forces transferred from the axle to the axle housing?

Via the C-lock and differential pinion shaft. By the inner axle seal and thrust washer. Through the bearing and the retainer plate located at the outer end of the axle housing. By the wheel hub assembly.

What is the purpose of the flats usually milled onto the bearing surface of the differential pinion shaft?

To allow the shaft to be secured by a threaded pin. To provide recesses for the axle shaft locking clip. To provide lubrication spaces between the shaft and the pinion gears. To hold the thrust washers in place axially.