A transfer case is a part of a four-wheel-drive system found in four-wheel-drive and all-wheel-drive vehicles. The transfer case is connected to the transmission and also to the front and rear axles by means of drive shafts.

Construction:

• The input shaft is connected to the gear box and carries on it a member having axial teeth.
• Two input shaft gears are free to rotate on the shaft. Each of these gears have bosses on the side which have axial teeth of the same pitch as the central member on the input shaft.
• Depending upon the movement of the transfer box gear lever, the central member and thereby the input shaft may be connected either to the small gear or to the big gear.
• There are two output shafts, one going to the front axle and the second going to the rear axle.
• The front output shaft is smaller in diameter and is supported inside the rear output shaft which is directly connected to the output gear.
• The front output shaft has fitted on it a shifter mechanism and also has splines over a small length of it, which when engage with the corresponding internal splines on the rear output shaft, connect the two shafts rotationally with each other.

Working:

• When the shifter mechanism A is in the centre so that no gear is connected to the input shaft, the drive is in neutral as shown in Fig.i.
• Fig.ii shows when the shifter mechanism A connects the input shaft with the big input gear, but the shifter mechanism B disconnects the front output of shaft from the rear output shaft. In this position, two-wheel drive with the high gear is obtained.
• In the same way Fig.iii depicts the situation with four wheel drive in low.

A transfer case is a part of a four- wheel- drive system found in four- wheel -drive & all-wheel-drive vehicles. The transfer case is connected to the transmission & also to the front & rear axles by means of drive shaft.

Construction:
i) The input shaft is connected to the gearbox & carries on it a member having axial teeth.
ii) Two inputs shaft gears are free to rotate on the shaft. Each of these gears have basses on the side which have axial teeth of the same pitch as the central member on the input shaft.
iii) Depending upon the movement of transfer box gear lever, the central member & there by the input shaft may be connected either to the small gear or to the big gear.
iv) There are two output shafts, one going to the front axle & the second going to the rear axle .
v) The front output shaft is smaller in diameter & is supported inside the rear output shaft which is directly connected to the output gear.
vi)The front output shaft has fitted on it a shifter mechanism & also has splines over a small length of it, which when engage with the corresponding internal splines on the rear output shaft, connect the two shafts rotationally with each other.

Working:
i) When the shifter mechanism A is in the centre so that no gear is connected to the input shaft, drive is in neutral as shown in fig 8.1.
ii) Fig:8.2 shows when the shifter mechanism A connects to the input shaft with the big input gears, but the shifter mechanism B disconnects the front output of the shaft from the rear output shaft. In this position, two- wheel drive with the high gear is obtained.
iii) In the same way, fig: 8.3 depicts the situation with four wheel drive is low.