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Pro Locker - Air Activated Diff Lock

Pro Locker - Air Activated Diff Lock


Experiencing life outdoors is best achieved behind the wheel of a 4x4. But, why is that when you finally take your 4WD out of suburb onto what’s meant to be its home-turf that even the smallest obstacle becomes too challenging for your brand new, shiny 4x4? 

Well, it’s all about traction. Traction describes the relationship or grip that your tyres have with the ground, and loss of traction is the 4x4’s number one enemy. Without traction, your prized vehicle will be about as useful as an exercise bike at a suburban gym.

Even though you've purchased a 4x4, its factory differential is designed for road use. To prevent premature wear on tyres, it allows for easy cornering by delivering torque to the wheel experiencing the least resistance. This process works well on bitumen, but when you go off-road, your engine will send all its power to the wheel that comes off the ground, essentially, leaving you powerless.

The TJM Pro Locker solves this problem with the flick of a switch. An innovative air locker, the Pro Locker effectively locks “traction-less” wheels and subsequently, the other wheels work harder to get you out. The Pro Locker allows you maximum traction and drive from all four wheels giving you the best possible chance of tackling formidable terrain. And all without getting your feet dirty. With the Pro Locker installed, you may never get stuck again.

Unique air operated piston style actuator eliminates the possibility of oil being pumped up the airline
Hardened thrust washers and size of locking ring make Pro Locker extremely strong in operation
Contains stronger materials and a thicker carrier compared to most standard differentials
Larger pinion gears are used in comparison to most standard differentials
No carrier modification needed other than the drilling and tapping of a bulkhead fitting port
Large pre-tensioned 3/8”
bolts hold the Pro Locker
hemisphere together
Patented design that has been used and proven in the field for over
20 years



To be tested anywhere in the Australian outback is challenging, but to be tested under ‘extreme’ competition conditions would leave most 4WDrivers shaking in their boots.

Luckily the TJM Pro Locker had been there before; 20 years before, again and again, as we researched and continued to improve its capability. Today the TJM Pro Locker stands alone.

With an innovative air operated differential locker that, at the flick of a cabin switch, allows you to send equal drive to both wheels and the unique piston style actuator eliminates the risk of oil entering the airline.

With a unique one piece cross shaft (instead of the usual three) adding to its strength, as does the hardened thrust washers, 3/8 bolts holding the hemisphere together and larger pinion gears.

And with a separate pneumatic system that has no internal ‘o’ rings or oil seals adding to its operational simplicity and low maintenance, whether you’re a hard core competitor or a weekend wheeler.


When a vehicle with four wheel drive engaged is driven in a straight line, the standard differentials in most vehicles allow equal transfer of engine torque to all four wheels. When the vehicle turns a corner, torque is delivered to the wheels that experience the least resistance. This principle ensures that the inside wheels will rotate freely and power is delivered to the outside wheel to prevent tyres from scuffing and wearing out prematurely.

Because the standard differentials transfer the torque to the wheels that encounter the least resistance, you will lose drive on loose/slippery ground or if one wheel is suspended in mid air. This becomes a problem as the wheel will spin and won’t allow the wheel on firmer ground to drive the vehicle out of a situation.

4x4 in a straight line

4x4 cornering

4x4 on a slippery surface


The operation of the Pro Locker differential is simple and straight forward. Utilising compressed air, the internal selector ring will engage the lock ring. Once the TJM Pro Locker is engaged it forms a solid link between the carrier and the side gears. The differential is now locked and will deliver equal drive to both axles. The vehicle that was once suspended in mid air can now have equal power delivered to the wheel on firmer ground and can be driven out of the situation.

Unlocking the differential involves the pressurised air being redirected through an exhaust port on the solenoid valve. The spring and the actuator pushes the selector ring back, which in turn pulls the locking ring back out of engagement with the side gear. The differential is now unlocked and the gears are free to differentiate as before.

4x4 in a straight line

4x4 cornering

4x4 on a slippery surface



Differential Casing

High strength SG iron - these pieces hold the solid one piece cross shaft & 4 pinion gears together by 8 high grade bolts, making the TJM Pro Locker one of the strongest locking differentials on the market.

Flange Cap Assembly

TJM’s extra thick flange cap features longer crown wheel bolts for extra strength. (where applicable).

Side locking gear

With extra large teeth & featuring a leading edge the TJM Pro Locker is one of the easiest to engage.

Pinion Gears

Thicker than standard case hardened thrust washers that are perfectly shaped to the internal spider gears.

Lock ring

When activated the case hardened lock ring has a full 10mm of engagement over the side locking gear.

Hardened One Piece Cross Shaft

This hardened one piece cross shaft is the key strength of the TJM Pro Locker.

Hardened Selector Ring

The all metal, hardened selector ring connects to the lock ring via 4 metal posts


The uniquely designed actuator works like a motor piston. The fork sits on top of the selector ring guiding it across when engaging or disengaging..

Heavy Duty Airline

This comes standard with the TJM Pro Locker. It will not pull out if hooked on rock or logs.

Solenoid Valve

Designed especially for TJM. Sealed against dust & moisture to IP65 standards. Machined & anodised from billet aluminium.

Pro Locker Switches Clearly Lit L.E.D

Switches are recessed into the switch block for protection against accidental engaging or disengaging of the TJM Pro Locker.


Did you know?

TJM released the Pro Locker into the market for a select few models and over six years on the TJM Pro Locker has endured intensive testing which has taken the already proven design and made it even tougher. Based on comparative advantages, thereis no doubt the TJM Pro Locker is superior to any other diff locker available today.

Be assured, the TJM Pro Lockers combination of simplistic design with components of exceptional strength and quality will leave you satisfied with your choice for years to come.