Lever escapement was invented in the mid-18th century, becoming more mature and steady. Most of horologes adopted the lever escapement at that time. George Daniels changed this situation by co-axial escapement, which is a modification of the lever escapement with some features of the detent escapement. Considered by some to be one of the most significant horological advancements since the invention of the lever escapement, the co-axial escapement functions with a system of 3 pallets that separates the locking function from the impulse, avoiding the sliding friction of the lever escapement. This makes lubrication of the pallets unnecessary and thereby eliminates one of the shortcomings of the traditional lever escapement.
In 1999, omega unveiled the first movement 2500 adopting co-axial escapement, and launched the new design co-axial movement 8500. So why adopt to the new escapement? The mechanics of this design must be considered in order to fully appreciate the benefits the Omega Co-Axial escapement offers in terms of reduced friction and greater stability of the watch’s rate over time.
Lever escapement
With regard to the escapement of wrist watch, it is critical to the efficiency of energy transfer and reliability.
The energy of mechanical watch come from deformation energy of the barrel. The wheels and lever escapement replenish energy.
Co-axial escapement
The technology is complex but there are some impressive advantages to the design when it is compared with the Swiss lever escapement.
With any watch escapement, energy has to be transmitted to the oscillator; this energy maintains the oscillator’s frequency. The impulse in a Swiss lever escapement involves the wheel tooth sliding along the inclined surface of the pallet. This sliding movement generates considerable friction, making optimal lubrication vital if the escapement is to function correctly.
Both clockwise and anti-clockwise impulses in a Swiss lever escapement are delivered indirectly from the escapement wheel through the anchor to the balance roller, resulting in an important loss of energy. The co-axial escapement’s clockwise impulse is given directly to the pallet on the balance roller by the teeth of the escapement wheel. As a result, the co-axial escapement benefits from greater mechanical efficiency which ensures more stable precision.
