Fred Bell highlights the key aspects to consider when selecting a wheeled loading shovel for waste handling applications
There are two clear stages involved in wheeled loading shovel selection: matching the performance and size of the machine to the application; and selecting the correct model available in that class.
The key demand for any materials handling equipment is to ensure that the processing of waste at a facility keeps pace with the incoming material. If there is a target volume of material to be moved per day, week, month, etc, work backwards from it to determine the optimum machine to achieve it.
As smaller machines require less capital investment and generally offer better fuel economy, it is most cost effective to select the smallest machine capable of achieving your productivity targets – taking into account any projected expansion.
Waste handling can involve a huge variety of materials, but the key considerations are the same when deciding on correct machine specification. It will be determined by what is being moved, where it is being moved from and to, and finally – how much of it needs to be moved.
The typical hourly productivity calculation (t/h) is as follows: density of the material handled (kg/m3) x bucket volume (m3) x the number of cycles which can be achieved in 50 minutes - an accepted industry standard as drivers can rarely achieve a full hour without interruption.
Density of the material in the bucket is integral to the total tonnage that can be moved and the size of bucket and machine required. This can vary dramatically between common waste materials.
The most common waste and recycling role for a wheeled loading shovel is to collect material from a ground level stockpile within a shed or store, transport it, then lift the waste and deposit it into another vessel such as a hopper or truck, before returning to the stockpile to repeat. This is one cycle and can be timed.
Therefore the machine must be small enough to enter, turn and exit the shed, yet have sufficient power and lift height to deposit the waste into the receptacle. It is important to factor in that the front edge of the bucket drops as it deposits material so in these circumstances it is this lower height which must be used to determine loading height.
Once these requirements are known, a simple calculation will determine the correct bucket size to meet the required tonnage per hour and then to identify a machine capable of lifting and loading that bucket to the required height when fully laden.
Eg, if broken glass is being loaded (approx. density 400 kg/m3) with a 2m3 bucket and each cycle takes 75 seconds (i.e. 40 cycles per 50 minute hour) then the following rate can be achieved: 0.4 x 2 x 40 = 32 tonnes per hour = 256 tonnes per day (8 hour day).
Wheeled loading shovels are articulated in design. When turning, the load moves to either side of the centre of gravity and the machine’s stability is reduced. As most cycles will involve cornering, the machine’s ‘full turn tipping load’ – the term for the weight of material loaded into the specified bucket which will raise any tyre from the ground when the machine is at full lock – is critical to the suitability of the shovel. This is a key consideration when selecting a machine.
Once size and performance parameters have been established, the merits offered by each available model in that class can be compared.
Fuel efficiency is a crucial factor as specifying a more fuel-efficient engine can lead to massive savings over a machine’s lifetime. Loader arm configuration also has a major impact on suitability. Wheeled loading shovels are generally available in Z-bar or 4-ram geometry, so ensure the model selected is available in the right configuration to afford the functionality needed.
Also important is suitability for the environment; if the model has sufficient protection against the rigours of the application, guards against threats presented by the materials loaded, manages dust levels, potentially corrosive or flammable materials and puncture risks.
Consideration of risk to infrastructure, other equipment and workers on site is also important. Ensure the manufacturer has built in suitable health and safety measures.
Downtime is a costly problem - whether it is slow response from engineers, lack of spare parts availability or theft. The level of support offered by manufacturers and their dealer network can be as influential as the performance of the machine itself and should be a key selection criterion.
Fred Bell is JCB’s Business Manager for Waste, Recycling & Demolition Industries