The gearboxes of the mixing group are epicyclical type. The first reduction is carried out by a pulley transmission equipped with a constant-velocity universal joint to keep the shafts syncronised. The low input speed to the gearboxes allows the lubrication oil to work at low thermal load. The connection between the gearbox and the tank is made with the exclusive connection sleeve, developed over the years to make any possible maintenance to the shaft supports easier and faster. This sleeve can be disassembled easily giving access to shaft support and in case of maintenance, the downtime for the plant is minimized.
The mixer tank is lined with Ni-Hard Cast Iron of 530HB minimum hardness. The mixing arms, with a low profile to avoid material build up, are made in Spheroidal Cast Iron. The mixing blades are made in Ni-Hard Cast Iron of 530HB minimum hardness. The large number of blades, their position and their orientation guarantee the right combination between the effects of rolling and circulation of the material during the mixing action.
Extra Rigid Tank
The stiffened frame of the tank eliminates the risk of deformation during the transport (also in container) as well as during the full load operation and guarantees the correct planarity of the shafts’ seals. The metal frame for aggregates hopper and the scales can be laid right on the mixer without additional supports.
Hydraulic Power Pack
The closing of the door is guaranteed by the pressure sensor included in the hydraulic circuit. In case of failure or blackout, a manual pump can be operated for the emergency discharge and closure.
The discharge door has a rubber seal that runs along its full perimeter. The eccentric rotation of the door sector guarantees that the rubber seal is always reached and compressed despite its wear and tear.
Shaft Supports and Seals
The modular support patented by SICOMA is made with two separate housings. The bearing is lubricated in long lasting oil bath. The seal, based on the exclusive system of the counter-rotating disks, is lubricated with liquid grease under controlled pressure.
The mixer is equipped with several sensors: thermal sensors for the motors and for the gearboxes, level gauges for the oil of the gearboxes and for the hydraulic power pack, level and pressure sensors for the automatic lubrication system. Upon request, Sicoma can supply the Black Box, an electronic system that records type, number and duration of possible anomalies and alarms during the operation of the mixer. The same device can be programmed for the preventive maintenance.
Top Cover and Inspection Platform
The high top cover (500mm) is equipped with two hinged hatches and does not have any post. It allows an easy access to the mixer for an accurate cleaning at the end of the shift or for both preventive and unscheduled maintenance resulting in a shorter shutdown of the plant. The inspection platform with stairs, included in the supply, is absolutely necessary for the safe inspection and maintenance of the mixer. Its effective modular design allows the installation to be extremely easy without the need of any crane or winch.
Swing Out Drives (SWOD Option)
This unique option for SICOMA Twin Shaft Mixers was developed over the last years to make any maintenance to the shaft supports easier and faster . The full drive assembly (Motor, Pulleys and Gearbox) is hinged to the side of the mixer tank and it can be swung out easily without the need of cranes or any lifting device.
In case of unplanned maintenance, the downtime for the plant is minimized, resulting in a extremely low maintenance cost.
The loading skip for the aggregates is available for the MAO mixers up to the size 6000/4000. The hoist has two grooved drums on the same shaft.
The skip cable has an anti free-fall block in case of cable failure while two limit switches constantly check its tension. Upon request, the double speed for ascent and descent is available, as well as an inverter based controller to customize speed at its best.
Batch Feeding System
Due to the particular reinforced structure, SICOMA Twin Shaft Mixers can be equipped with a Batch Feeding System stacked on the tank using the top fixing plates on the tank frame. This system is composed by Aggregates Holding Hopper, Cement Scale, Water Scale and Air Bag. Being everything preassembled at the factory before the shipment, the installation time at the jobsite is extremely short.
High Pressure Washout
Two high pressure water pipes are placed above the shafts with as many nozzles as the number of arms. These spray bars are operated by a gearmotor and rotate so that the jets reach every spot for an effective cleaning. The washout has to be carried out at the end of each mixing cycle and the waste water is used for the next mixing.
Slow Motion Drive
This option is based on an auxiliary motor which can rotate the shafts at low speed (1 RPM). By using a button switch, the shafts can run safely also with the inspection doors open. The cleaning as well as the regular maintenance (such as periodic blade adjustment) are simplified and faster. We recommend to choose the Manual Control Panel including all devices to operate the Slow Motion Drive.
High Pressure Water Unit
With a reservoir of minimum 200 litres, the High Pressure Water Unit supplies the spray bars installed in the mixers using a piston pump driven by a motor with minimum power of 15 kW. The pressure and flowrate are selected depending on the mixer size (min 60 Bar).
Manual Control Panel
The mixer can be equipped with the Manual Control Panel which can operate the mixer in Manual Mode with the following buttons: Start/Stop of the mixer motors, Open/Close Discharge Door and Emergency Stop. This Panel can also operate the Slow Motion Drive, if present.
Reduced Discharge Door
The reduced size of the discharge door allows the use of a small discharge chute. As a consequence, the supporting structure of the mixer can be shorter compared with the standard twin shaft mixers.
Double Discharge Door
The mixer can be equipped with two independent discharge doors to pour the concrete in two different places. One of the limitations of the twin shaft mixers is then overcome.
Bomb Bay Door
All SICOMA Twin Shaft Mixers can be equipped with the Bomb Bay Door which allows the bottom of the mixer tank to be opened for nearly half of its surface. The discharge is extremely fast also in case of low slump concrete. This option is particularly important in case of RCC production and loading on dump trucks.