The paper introduces the structure and work processes of outside auger hollow claw tipped mechanical sampler for coal. Twenty sets of claw tipped sampler performance tests show that: The design of inner hollow cylinder-type (180 mm) can ensure to take a coal sample with nominal top size of 60 mm._x000D_
Built-in self-cleaning piston pusher ensures no adherence and blocking of the sample. The operation practices show that the mechanical sampler can operate in order for taking coal sample with up to 16 per cent of total moisture._x000D_
Claw closing design can avoid sample leaking or spilling during the claw lifting and ensure the integrity of primary increment._x000D_
Ultrasonic positioning device makes the sampler capture the materials no less than 10 cm from the bottom of the wagons, basically meeting the requirement taking full depth of the sample._x000D_
The precision and bias test indicates that the moisture and ash have no relative bias under the sampling process; the sampling precision is in accordance with the requirement in IS013909._x000D_
At present, the spiral mechanical sampler is widely used for coal sampling but there are many limitations during application, for example: It is difficult to capture a large size sample, so the size range of a coal sample taken is limited._x000D_
There is easy adhering or blocking for high moisture coal, which will result in the mixture of different increments, wear of sampler and the difficulties for cleaning and maintenance of sampler._x000D_
It is difficult to capture the coal sample at lower than 30 cm from the bottom of the wagons, in order to avoid damage of the vehicle._x000D_
It is possible for coal sample loss and spilling during the sampler lifting, due to the unsealed sampler._x000D_
For the outside auger hollow claw tipped mechanical sampler designed for solving the above problems, the opening distance of the claw is the opening size of the sampler and makes the size range of the coal sample to be taken wide. During sampling, the two pieces of claws open and the sampler rotates vertically downward to capture an adequate coal sample after reaching the specific point. Then the two pieces of claws close tight automatically to ensure there is no coal leaking or spilling. The inner pusher of the sampler will prevent from the adherence and blocking of the coal sample effectively.CITATION:Zhang, B, Pi, Z-Y and Wen, S, 2012. Outside auger hollow claw tipped mechanical sampler for coal, in Proceedings Sampling 2012, pp 41-44 (The Australasian Institute of Mining and Metallurgy: Melbourne).