Improved Single-shoe Park Brake

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Improved Single-shoe Park Brake

Introduction: Why do we use drum-in-disc park?

Four wheel disc brake is becoming a widely adopted braking configuration in modern cars for its consistent performance. Most disc brake rotor has a top-hat section which allows fitment of a drum-in-disc park b rake within,making extra packaging space unnecessary.

Duo-servo shoe arrangement is well known for its high torque output and is ideally suited for packaging in a small environment

Integral park brake caliper because of its low inherent servo assistance, needs a significantly high hand effort to secure a hill hold, particularly when the vehicle is heavy, or when the Iining coefficient of friction is low, typically required as a solution when noise is an issue with service braking.

Drum-in-disc park b rake concept allows the service brake to utilize a lower friction, generally quieter friction material,leaving the task of hill holding to a separate brake without compromising any performance.

Evolution of single shoe park brake

Single shoe brakes date back to the 1930' flexible steel shoe and a unique lining grinding technique developed 20 years ago had raised the benchmark for hill hold performance,particular with a set of unburnished ("#00CCFF")linings. The lining is ground to match the drum diameter when the shoe is expanded to its apply position This results in a Perfect mating contact between the lining and the drum when the brake is applied. The combined effect of this intimate contact and the semi-flexible nature of the steeI shoe enables an efficient servo build up of lining Pressure that is attributable to its extraordinary high level of torque output.

Problem of current single shoe

While the output performance of a single shoe is excellent it requires special attention to the shoe geometry and its construction in order to support the high level of pressure generated. Current shoe suffers a lack of lining support area at where the pressure is highest...the shoe platform tapers to a much reduced area towards the shoe tip In addition the already small platform supporting the lining is further disrupted by a number of voids left there as a result of the shoe manufacturing Process.

Under heavy duty applications, lining at the shoe tip often fails(breaks and or shears off) because of lack of Proper support and adhesion. Performance suffers as a result.

Youfin's solution

Youfin's constant benchmarking and R&D effort has successfully developed an innovative shoe manufacturing Process that eliminate its current short coming

The new shoe geometry includes a larger and un-disrupted surface at the tip of the shoe Platform This enhanced topography not only enables an increase in lining area locally, it also improves structural support to the lining allowing maximum performance and durability potential of the shoe to be achieved

In addition, contrary to the original 'expand-and-grind' method, a non expanded, cam profile controlled or numerical cont rolled lining grinding technique has beendeveloped by Youfin to complement the shoe platform upgrade.

This is consistent with Youfin s adopted philosophy of continuous improvement and continuous innovation.

This feature is currently protected by a provisional patent application.

Size range of Youfin single shoe and park brake assembly

Nominal shoe Dia.	Φ168	Φ175	Φ190	Φ210
W	46.25	46.25	46.25	46.25
A	2.5	2.5	2.5	2.5
B	25	25	25	32
H	13.5	13.5	15	15.5