Method and apparatus for converting transfer cases for four-wheel drive vehicles

An improved means for adapting for optional part-time two-wheel drive operation a full-time four-wheel drive vehicle of the type having forward and rear axles, a transfer case, a main drive shaft operatively connected to the transmission of the vehicle, forward and rear drive shafts operatively connected to said forward and rear axles, the transfer case being of the type having differential gear means including a differential carrier member operatively connected through a transfer case drive shaft to said main drive shaft, pinion gear means rotatably mounted within said carrier member, and forward and rear output drive gears adapted to be engaged with said pinion gear means for being driven thereby, the forward and rear output drive gears being operatively connected by forward and rear output shafts to said forward and rear drive shafts for driving said forward and rear axles, respectively, said rear output drive gear comprising bevel gear means having teeth on the forward side thereof running substantially radially outwardly from said rear output shaft, said differential carrier member being of the type having a generally tubular inner connecting member adapted for affixing about said transfer case drive shaft, an outer tubular member concentrically disposed about said inner connecting member, elongated cylindrical shaft means extending radially through the annular space between said inner and outer members connecting them and affixing them in said concentric relationship, said improved means comprising:

• means for replacing said pinion gear means comprising a substantially tubular body portion compatibly sized to fit within said annular space when said pinion gear means is removed therefrom, engaging means along one end of said tubular body portion for engaging said radially extending shaft means when said body portion is positioned in said annular space, and engaging means along the other end of said tubular body portion for engaging said rear output drive gear for locking said tubular body portion therewith,
• said engaging means along said other end of said tubular body portion including a conically tapered gear teeth portion which faces inwardly toward the axis of said tubular body portion for compatible meshing with said teeth of said rear bevel gear means,
• said engaging means along said one end of said tubular body portion comprising axially aligned slots in said body portion sized to compatibly engage said shaft means,
• thrust bearing means for positioning about said transfer case drive shaft interposed between said inner connecting member and said forward output shaft for bearing axial thrust forces therebetween, and
• means for locking and unlocking the front hubs of said vehicle to permit optional free-wheeling of the front wheels thereof.

The method for adapting for optional part-time two-wheel drive operation a full time four-wheel drive vehicle of the type having forward and rear axles, a transfer case, a main drive shaft operatively connected to the transmission of the vehicle, forward and rear drive shafts operatively connected to said forward and rear axles, the transfer case being of the type having a differential carrier member operatively connected through a transfer case drive shaft to said main drive shaft, the differential carrier member having a generally tubular interconnecting member affixed about said transfer case drive shaft, an outer tubular member concentrically disposed about said interconnecting member with an annular space therebetween, shaft means extending radially through the annular space between said inner and outer members connecting them and affixing them in said concentric relationship, and differential pinion gear means rotatably mounted on said shaft means, forward and rear output drive gears engaged with said pinion gear means for being driven thereby, the forward and rear outward drive gears being operatively connected by forward and rear output shafts to said forward and rear drive shafts for driving said forward and rear axles respectively, and clutch means for optional clutching connection of the differential carrier member to the forward output shaft, comprising:

• removing said pinion gear means from said shaft means,
• interconnecting said differential carrier member and
• said rear output drive gear with a locking member having means at one end thereof engaging said shaft means, and gear teeth at the opposite end thereof meshing with said rear output drive gear,
• for thereby locking rotationally together said differential carrier and said rear output drive gear,
• and installing locking-unlocking hubs on the front wheels of said vehicle to permit optional freewheeling of said front wheels.

The method for adapting for optional part-time two-wheel drive operation a full time four-wheel drive vehicle of the type having forward and rear axles, a transfer case, a main drive shaft operatively connected to the transmission of the vehicle, forward and rear drive shafts operatively connected to said forward and rear axles, the transfer case being of the type having a differential carrier member operatively connected through a transfer case drive shaft to said main drive shaft, the differential carrier member having a generally tubular interconnecting member affixed about said transfer case drive shaft, an outer tubular member concentrically disposed about said interconnecting member with an annular space therebetween, shaft means extending radially through the annular space between said inner and outer members connecting them and affixing them in said concentric relationship, and differential pinion gear means rotatably mounted on said shaft means, forward and rear output drive gears engaged with said pinion gear means for being driven thereby, the forward and rear output drive gears being operatively connected by forward and rear output shafts to said forward and rear shafts for driving said forward and rear axles respectively, and clutch means for optional clutching connection of the differential carrier member to the forward output shaft, comprising:

• removing said generally tubular interconnecting member from said transfer case drive shaft,
• separating said generally tubular interconnecting member, said shaft means and said pinion gear means from said outer tubular member,
• removing said pinion gear means from said shaft means, so that there is no driving connection between said forward and rear output drive gears,
• reassembling said generally tubular interconnecting member and said shaft means with said outer tubular member,
• forming a locking member having slots in one end thereof and teeth in the opposite end thereof which taper conically toward the axis of said locking member,
• then positioning said locking member with the teeth thereof meshing with said rear output drive gear and said shaft means received in said slots, for thereby locking rotationally together said differential carrier and said rear output drive gear,
• and installing locking-unlocking hubs on the front wheels of said vehicle to permit optional freewheeling of said front wheels.