How the GCD Works

HOW THE GEARLESS CENTRE DIFFERENTIAL WORKS

Toyota Landcruiser HZJ78/79, VDJ70 series and GDJ70 series Transfer Case Conversion

The Gearless Centre Differential power divider converts the Toyota Landcruiser transfer case into the perfect full-time four wheel drive transmission. A 4WD vehicle fitted with a conventional PART-TIME transfer case suffers from the destructive forces of axle wind-up when operating continuously in 4WD on hard surfaces.

Two major problems occur with standard part-time 4WD transmissions.

1. Drive train wind-up causes wheels to continually fight each other by skipping and skidding as they attemp to equalise the torque imbalance and differences in wheel speed.
2. The vehicle is pushed straight ahead during cornering and is therefore difficult to handle and control.

The Gearless Centre Differential is the perfect answer for heavy duty full-time 4WD use.

• Safer operation due to the driver having much better control of the vehicle.
• Smooth cornering with full traction at all times.
• Fully automatic in its lock/ unlock operation.

Models available for the Toyota HZJ78/79, VDJ70 and GDJ70 series range are:

• A low range only model for the dedicated underground vehicles.

Primary advantages of the Gearless Centre Differential:

Safety.  We all know the importance of workplace safety and the emphasis which is placed on employers providing a safe work environment for their employee’s.  The Gearless Centre Differential makes vehicles more controllable and easier to handle, especially in the difficult conditions that exist in minesites.  Tight cornering, and cornering in general is a much easier task for the driver with a Gearless Centre Differential installed.

A large number of mines are now using the Gearless Centre Differential and receiving the benefits of much reduced downtime and maintenance on driveline components. Added to this are the accumulated savings on labour and spare parts like CV joints, knuckles, clutches, and diffs, etc. Our recorded information shows that one mine over 10 years has extended the life of CV joints from 300 to 2100 hours.  With the true cost of replacing CV Joints being somewhere between $1500 and $2000, the GCD will soon pay for itself in savings on repairs and downtime.

The unlocking/locking torque balancing operation of the Gearless Centre Differential is completely automatic and does not require driver intervention. The elimination of tight corner braking effect, which pushes the vehicle straight on, makes the vehicle easier and safer to drive with greatly improved traction to all four wheels.

Fitting takes under 3 hours without removing the transfer case. Once installed, no further adjustments are necessary apart from routine transfer case oil changes.

HOW THE GEARLESS CENTRE DIFFERENTIAL WORKS to produce the perfect full-time 4X4 transmission

The Central Drive Assembly in a Gearless Centre Differential utilises Detroit Locker technology. These have been used in car, truck, 4WD and racing differentials for over 40 years and are well-proven for their rugged strength and durability.

Simply put, the Gearless Centre Differential transforms the transfer case into a third differential, automatically working to equalise the torque imbalance developed between the front and rear prop-shafts as the axles wind up during cornering in a 4WD.

The Gearless Centre Differential unlocking mechanism works on a teeth ramping principle between two spring loaded clutches and a Central Drive Unit.

During cornering, one prop-shaft (usually the front) tries to spin faster (winds up) as it is rotated by the faster turning outside front wheel. This produces a torque imbalance between the front output shaft and the rear output shaft of the Gearless Centre Differential.

As the wind-up builds, the Gearless Centre Differential front clutch teeth automatically slide smoothly up a cam ramp until they disengage briefly. This disengagement allows the torque to release in the prop-shaft, and once equalised, the clutch teeth automatically re-engage. All in a fraction of a second and so smooth as to be almost imperceptible to the driver who is free to concentrate on the job at hand.

The constant differential action during cornering keeps driving torque to the front and rear axles evenly balanced, eliminates driveline wind-up and prevents premature CV joint failure, driveline component wear, vehicle instability, and tight corner braking effect.