HF2A Transfer with Mechanical Locking Type


Center Differential and Transfer

1. Transfer

This transfer is a two-speed (Low- High) type. The center differential is located inside the low speed output gear of the output shaft. Power is transmitted to the center differential from the transmission via the input shaft, the high or low speed idler gear and the high or low speed output gear.

2. Power transmission

Low-speed Mode

3. Center differential

The center differential gear is the bevel gear type and the center differential limit control mechanism is the mechanical locking type. The center differential gear unit consists of two pinion gears. During straight-ahead driving, when there is no speed differential between front and rear wheels, the center differential pinion gears do not revolve. When a speed difference between the front and rear wheels occurs due to cornering, etc., the center differential pinion gears revolve, absorbing the speed difference.

4. Shift fork slide system

A shift fork slide system which uses a shift fork shaft to switch between the “L4” range and the “H4” range, and to carry out locking of the center differential, is used. Switching between low and high speeds is accomplished by the transfer lever, while locking of the center differential is accomplished electrically by a motor driven transfer shift actuator.

5.Transfer shift actuator

Drives motor and changes driving mode (“Free” or “Locked”) in accordance with signals from 4WD control relay.

<1>Motor control limit switch When the contact plate slides under the contact springs while turning with the rotation of the driven gear, the electrical connection between it and the contact springs changes, causing the motor to stop in the optimal position at all times.

<2>Spiral springs If the operating resistance of the front drive shift fork shaft is large, the rotational force of the motor is partially “stored” in these springs. Afterward, when the operating resistance is reduced, the spring force causes the front drive fork shaft to slide.

Center Differential Locking System

1. General

The center differential locking system mechanically locks the center differential, forcing power to be transmitted evenly to front and rear differentials. If any one of the wheels is stuck, the other three wheels also spin. Therefore, locking the center differential distributes power it equally to all four wheels and makes it possible to get out.

2. Components

The system consists of the following parts.

(1)Center differential lock indicator light Indicates condition (free or locked) of center differential to driver

(2)Center differential lock switch Switches center differential control mode between “Lock” and “Free”.

(3)Center differential lock indicator switch Detects that center differential is locked.

(4)”L4″ position switch Detects transfer shift lever position (“H” or “L”)

(5)Center differential lock control relay Locks or unlocks center differential depending on signals from various sensors.

(6)Transfer shift actuator (1/2) 1. Features of range switching mechanism The chart on the left shows in which conditions each position of the transfer shift lever and differential lock switch are used.


When the transfer shift lever is in the “L” range position, the L4 position switch is on, so center differential lock control relay operates regardless of whether the differential lock switch is on or off, and the motor turns, causing the center differential to be locked.

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