Synchromesh Engagement.

Most modern cars are fitted with a synchronized gear box from factory. In a synchromesh gearbox, to correctly match the speed of the gear to that of the shaft as the gear is engaged, a collar initially applies a force to a cone-shaped brass clutch attached to the gear, which brings the speeds to match prior to the collar locking into place. The collar is prevented from bridging the locking rings when the speeds are mismatched by synchro rings (also called blocker rings or baulk rings). The synchro rings have a sloping engagement so as long as they drag rotationally, they hold the dog clutch out of engagement. The brass clutch ring gradually causes parts to spin at the same speed. When they do spin the same speed, there is no more force on the sloping surfaces of the synchro rings, and the dog clutch is allowed to fall in to engagement. In a modern gearbox, the action of all of these components is so smooth and fast it is hardly noticed.
The modern cone system was developed by Porsche and introduced in the 1952 Porsche 356; cone synchronizers were called "Porsche-type" for many years after this. In the early 1950s only the second-third shift was synchromesh in most cars, requiring only a single synchro and a simple linkage; drivers' manuals in cars suggested that if the driver needed to shift from second to first, it was best to come to a complete stop then shift into first and start up again. With continuing sophistication of mechanical development, however, full synchromesh transmissions with three speeds, then four speeds, and then five speeds, became universal by the 1980s. Reverse gear, however, is usually not synchromesh, as there is only one reverse gear in the normal automotive transmission and changing gears into reverse while moving is not required.
Synchromesh engagement is best done with slow movement of the gearstick . It may also be noted that synchromesh gear engagement is best done at lower engine speeds. Gear engagement with synchromesh also requires a short amount of time to take place, it is not instantaneous. This all differs completely from dog –engagement where gear selection is instantaneous, at any engine speed and must be actioned quickly for proper gear selection.
Main limitations of synchromesh gearboxes are slow shifting at very high RPM (Eg 9000rpm) and Slow gear selection when rapidly decelerating (Eg selecting 1st gear for a hairpin) as well as the need to use the clutch.

Gear Selection with Dog Engagement Gearsets
For successful shifting with a dog engagement gearset, one needs to have an understanding of how the dog mechanism operates.
Gear engagement is facilitated by what could be plainly described as numerous large teeth (dogs) that mate into openings machined into another surface, that often being the driven gear. Unlike the synchro engagement, the two rotating gears are operating at different speeds (unless the revs have been matched) and there is no synchronising mechanism to assist in bringing them up to a synchronised (equal) speed.
The number of dogs and the size of the openings determine the window of opportunity that the dogs have to engage on the shift event. It is for this reason that often we find smaller numbers of dogs offering a better shift quality, although with increased noise on the shift.
If the dogs do not line up to facilitate a gear engagement, the faces of each opposing surface (dogs) will clash and over time can wear. Wear will depend on the speed of the dogs and the force applied.
It is timely to point out at this time that Albins dogs have pentagon shaped surfaces to deflect the dogs apart on a miss-shift. This drastically enhances dog-life.
“Proper” gear selection to minimise clashing of dogs is achieved by fully moving the dog ring as rapidly as possible from one gear to the next, preferably with the engine's driving load removed until the shift is completed. (The opposite is true of a synchromesh gearbox as used in passenger cars, where slow movement helps).
Remember there will be no dog wear when the dogs are fully engaged (car is in-gear). The damage can only take place when initiating contact during a shift, (miss-shifting) therefore this event must be made as short as possible. If a driver moves the gear lever slowly, or if the linkage is poorly secured, dog wear will occur in various degrees. Lightweight and secure gear linkages will assist with gear selection and reduced dog wear.
It is probably worth mentioning here that dog wear is inevitable to some degree, but shift “style” amongst other things will have a bearing on the amount of wear experienced.

Albins Power Shift.
The movement of the dog ring is powered and the engine is cut / re-instated in a co-ordinated manner. Gear-shifts take milliseconds. This system produces near zero dog wear when set up properly. It is applicable to the Albins AGB Transaxle product with Powershift option.

Manual Gear Shifts with engine cut.
This system is almost as good as an automated one as long as the driver selects the gear swiftly. This is applicable to the AGB transaxle product but may also be adapted to many Albins Dog change gearsets. With this system it is especially important to swiftly select the next gear ultra fast, otherwise the engine will be reinstated during partial dog engagement, causing damage.

Manual Gear Shifts without engine cut.
The best method involves the driver releasing the throttle sufficiently to allow the dog ring to be pulled out of engagement. The driver will then experience the dog ring engaging with the next gear and the throttle can be re-applied . With practice this can be done in milliseconds and the driver will soon learn to move the gear lever faster than he can move his foot off and back on to the throttle. Therefore the effective method is to apply load to the gear lever with your hand and then lift the throttle foot off and back on to the pedal as fast as physically possible. In removing the throttle, the loaded gear lever will almost involuntarily shift to the next gear before the throttle is re-applied.
One other method of shifting is to load the gear lever with your hand, stay flat on the throttle and dab the clutch to release the dog ring. Clutch abuse in this situation may be an issue.

What NOT to do.
The most destructive method of shifting gears is to attempt to change gear in a `passenger car / synchromesh` way. This involves slow shifting and use of the clutch, i.e. lifting off the throttle, depressing the clutch, moving the gear lever slowly, releasing the clutch and applying the throttle.

Successful down-gear selection, has similar rules applied regarding the speed of shift. Unloading the dogs is done in the opposite manner obviously. Whilst braking, the dogs must be unloaded by either touching the throttle pedal or by depressing the clutch. However, one quick touch of clutch or throttle is appropriate per shift. Continued pressure on either of these will accelerate dog wear. Blipping the throttle just before engagement is advisable as this will aid engagement and match the revs’ with the speed of the car on deceleration.
For easer downshifting make the downshifts as late as possible in the braking area at a speed that is close to the lowest speed required to negotiate the corner.
In this scenario the rev drops between each gear are then much lower. Many drivers make the common mistake of downshifting as soon as they begin braking, causing unnecessary dog wear.

How do I know I have done dog-damage to my gearbox?
Typically, you will experience the car jumping out of gear and becoming difficult to get into gear. The dogs that hold the car in a particular gear have worn to the point where they no longer can maintain engagement when power is applied or in some cases, when the car is decelerating (opposite dog faces are worn).
In a “H” Pattern tyle of transmission this damage typically does not cause any other damage to the gearbox at this point apart from fragments of damaged dogs being present in the gearbox lubricant, which can cause resultant damage. However in a sequential transmission, worn dog rings that reach the point of pushing each other out of engagement may cause serious damage to other components within the shifting mechanism.
It is also worth noting that the general design and condition of the shift mechanism can have a significant affect on shift quality and life of the dogs. If the gear shift is rod operated, ensure that all joints are run as straight as possible and are free of any binding. If the gear shift is cable operated, ensure that the cable is free of any kinks and operate freely without bind.