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Module 270202eB — Heavy-Duty Manual Transmissions and PTOs (Part B)

Focus: lubrication systems, lubricant selection, filtration, oil pumps and coolers, PTO operation, actuation methods and common replacement parts. Answers target NAIT exam depth — no soft options.

What is the primary factor that dictates the service life of bearings, shafts, gears, and thrust washers in a heavy-duty transmission?

When referencing the manufacturer’s recommended lubricant chart, what three criteria must be considered when selecting the appropriate lubricant for a heavy-duty transmission?

According to Table 1, which lubricant is specified for use in highly loaded gears and hypoid gear applications?

Based on the manufacturer's recommendations provided in Table 1, what critical warning is given regarding the lubricant selection process?

The most common lubrication method used on all transmissions is the splash lubrication system. How does this system ensure the upper components, such as the mainshaft and upper countershafts, receive oil?

To ensure oil is directed to critical internal areas, such as the roller bearing on the reverse idler shaft, the transmission housing often includes what physical feature?

In a heavy-duty transmission, what component is often bolted to the shift bar housing to direct oil thrown from the splashing system to critical areas?

In some transmissions, a pressure type lubrication system is incorporated alongside the splash system. Where is the small eccentric shuttle type oil pump typically located?

What action occurs if the oil cooler lines are plugged on a transmission utilizing an integral oil pump with a relief valve?

Heavy-duty transmissions that rely on splash lubrication typically filter oil by means of:

When a pressure pump system is used, what additional component is utilized on the suction tube to assist the magnets in trapping foreign material in the oil?

If a transmission is not equipped with an internal oil pump, an optional externally mounted pump may be used. Where does this external pump typically receive its oil supply?

What is the definition of an auxiliary drive system, such as a power takeoff (PTO)?

Which types of auxiliary drive systems are always driving whenever the engine is turning?

What is the disadvantage of a rear engine-mounted auxiliary drive connected to the flywheel housing?

A power tower auxiliary drive unit is commonly used on oilfield trucks to drive heavy-duty winches. To what component is this unit typically bolted?

What enables the operator to vary the speed and torque output of an auxiliary transmission top-mounted power takeoff (power tower)?

Auxiliary PTO bolt-on units are available in two specific mounting configurations. What are they?

A drop box differs from a transfer case in its primary function because the drop box:

Which accessory drive system is used when large amounts of torque are required, and the main transmission must be in a gear to deliver the necessary speed and torque?

PTO output drive shafts constructed of tubular material are designed specifically for which applications?

The power flow through a PTO may include one to three gears before driving the output shaft. What is the consequence each time a gear is added to the PTO power flow?

What critical safety step must the operator ensure before engaging a power takeoff unit?

Engaging the PTO while the transmission gears are still turning will result in:

The cable actuated PTO system is essentially what type of mechanism?

On heavy trucks equipped with compressed air for the braking system, the PTO may be activated using air to move which specific component?

What is the primary functional advantage of a Clutch Shift Actuated PTO (also called power shift or hot shift)?

How do Clutch Shift PTOs achieve engagement, unlike traditional PTOs that use sliding gears?

The Indicator Switch used in most PTO systems serves what purpose?

When a single gear adapter housing is sold to a customer to facilitate PTO installation due to obstructions, what critical functional change must the parts technician remind the customer about?

Power takeoffs generally receive lubrication from the major component to which they are attached. What is the procedural consequence once the PTO is installed?

The gasket installed between the PTO and the transmission provides which two essential functions?

What is the maximum number of gaskets recommended to be installed between the PTO and the transmission mounting surfaces?

If more than four gaskets are required to achieve the proper backlash during PTO installation, what replacement component must be used instead?

The process of setting the proper backlash using selective thickness gaskets is necessary to provide what feature in the meshing gears?

To adapt a six-bolt PTO to an eight-bolt opening so that it may be installed in a different location, what component is required?

When an adapter plate is used to mount a PTO, how many gaskets are required at minimum?

When a transmission is opened for repair, what essential maintenance consideration should a parts technician remind a customer about, regarding low-cost components that ensure a trouble-free repair?

If a customer is replacing a failed transmission shaft, which related sales items should the technician recommend, according to Table 2?

Which specific components in the list of common PTO replacement parts require special care and attention because they are susceptible to wear and leakage?

Why must a parts technician provide the model number from the PTO tag when ordering replacement parts for a PTO assembly?

What type of PTO output shaft material is used in standard applications not requiring extremely high torque or RPM?

In the context of core management for remanufactured transmissions, if a customer returns a core that requires tear down and inspection, what must the parts technician provide?

What is the fundamental purpose of the core charge system used for remanufactured components?

When the transmission uses the pressure type lubrication system, the oil is typically supplied to the pump via which component?

What type of lubricant is typically recommended for use in transmissions when the ambient temperature is below −12 °C (10 °F), according to Table 1?