Main Structure and Operating Principle
“Lv Ye” transit mixer truck of our company adopts dedicated mixer truck chassis, originally imported
elements are adopted for its hydraulic pump, hydraulic motor, reduction gears, etc., and its superstructure has
advanced design, sophisticated manufacturing, reliable performance, which featuring with excellent concrete
mixing uniformity, high feeding and discharging efficiency, low discharging residual ratio, etc., with extensive
use in such building works as urban construction, road, railway, water and electricity and ports.
Transit mixer truck consists of dedicated vehicle chassis, hydraulic drive system, water supply system,
mixing drum, control system, feeding and discharging device and rack, etc. (see Figure 1).
1.Hydraulic drive system 2.Pressure water cleaning system 3.Front support 4.Tank body 5.Rear support
6.Staircase 7.Feed hopper 8.Discharge hopper 9.Chute device 10.Secondary beam assembly
1 Hydraulic drive system
Hydraulic system is the closed one, mainly consisting of hydraulic pump, hydraulic motor, radiator, high pressure pipe and low pressure pipe, etc. (see Figure 2).
1 Hydraulic oil tank 2 Oil suction rubber hose 3 Oil return rubber hose 4 Internal circulation rubber hose of pump motor 5 High pressure rubber hose 6 Motor 7 High pressure rubber hose 8 Oil pump
Mixing drum is powered by automotive engine, and it is driven by the reducer through closed hydraulic drive system consisting of manual variable displacement servo pump, axial plunger constant displacement motor and hydraulic accessories. Hydraulic pump is equipped with manual servo regulator, which can adjust hydraulic oil displacement and direction to control mixing drum direction and speed, and stepless speed adjusting can be conducted for forward and reverse rotation of the mixing drum. Temperature control cooler can effectively control the temperature of hydraulic oil, the cooler fan is turned on when hydraulic oil temperature of the hydraulic system reaches about 55 °C and the fan stops when the temperature drops to 50 °C so as to ensure the normal operating temperature of hydraulic oil. In normal operation, oil suction filter accuracy of the hydraulic system is not more than 10 μm.
2 Water supply system
Pneumatic water supply system is adopted (see Figure 3).
1 Water tank 2 Water level display pipe 3 Air pipe 4 Reducing valve 5 Inlet valve 6 Drain valve 7 Water feeding pipe 8 Rubber hose for cleaning
Pressure-type water tank volume contains 300 L and 400 L, and the user can select as required. After being filled with water by water pipe, water tank provides compressed air by automobile air reservoir via reducing valve. Under the pressure of the compressed air, water in the water tank enters into the mixing drum through water pipe to add water or wash. In concrete transport, concrete slump is relatively low due to water evaporation and fails to meet engineering requirements, the mixing drum shall be filled with appropriate water and then it rotates for 30 turns at a specified speed to meet the uniformity requirements. Water in pressure
water tank can be sprayed from hydraulic giant via rubber hose for cleaning to wash the car body. Pressure of reducing valve shall be set as 0.35 MPa, the pressure of safety valve shall be set as 0.5 MPa, and no change shall be made arbitrarily for safety.
3 Mixing drum
Mixing drum assembly is the main component of the transit mixer truck, which mainly consisting of tank body and two sets of helical blades. What’s more, the tank body consists of the reducer flange, back cone, middle drum, front cone, track and manhole, and two sets of helical curved surfaces inside the mixing drum are welded according to curve graph through six complex blades to ensure that the helical curve turns into Archimedean curve and logarithmic function curve, which is Archimedean curve from the end face and logarithmic function curve from axial direction. Crateriform feed hopper can ensure a successful feeding, and blades with complex shape welding to helical line can realize the three-dimensional concrete mixing so as to ensure the uniformity, no segregation and invariable slump of concrete. The mixing drum body is equipped with manhole for repair inside the tank. The whole mixing drum is installed above the support, front mixing drum is connected with reducer of the drive system, and the rear is supported by two riding wheels.
4 Control system
Transit mixer truck manufactured by us has two types of control system for the user to select, namely, three-side mechanical control system and flexible shaft controller type control system respectively. Standard configuration of the truck is the three-side mechanical control system.
(1) Three-side mechanical control system: Equip with linked control handle at the left and right side of the rear and control the flow and flow direction of hydraulic pump by swinging the control handle leftward and rightward to achieve the forward and reverse adjusting of the mixing drum; push the handle upwards to accelerate the accelerator speed of the engine, and make stepless speed regulating of the mixing drum available within a range of 18-0-18 r/min by regulating the control handle to the different positions. The cab shall also be provided with one control handle to achieve the forward and reverse control of the mixing drum.
Note: When using the control handles at the two sides of the rear, the handle locking device inside the cab
shall be opened first (by counterclockwise rotating the handle).
(2) Flexible shaft controller type control system: The control system consists of one standard controller assembly and two flexible shafts, and there are two control handles on the controller. One handle is connected with oscillating bar of the hydraulic pump through flexible shaft, which is used for the control of the flow and flow direction of the hydraulic pump so as to achieve the forward and reverse rotation of the mixing drum. Another is connected with the engine accelerator through flexible shaft for the control of the engine speed. During handle adjustment, the handle must be counterclockwise rotated to make the self-locking release, and the handle shall be clockwise rotated to complete self-locking after the operation. Stepless speed regulating of the mixing drum within 18-0-18 r/min can be made available by controlling the two handles simultaneously to make them at the different places, and the positions of the handles can be locked after the mixing drum speed is determined. Refer to operation instruction nameplate for the specific operation. Meanwhile, the cab is also provided with one control handle for the easy operation of the driver to realize the forward and reverse rotation control of the mixing drum.
Note: When using the control handles at the two sides of the rear, the handle locking device inside the cab shall be opened first (by counterclockwise rotating the handle).
5 Feeding and discharging device
Main functions of the feeding and discharging device are to feed the mixing drum and unload the concrete to the required location, and its device is at the rear of the delivery wagon. See Figure 4 for the structure.
1 Feed hopper 2 Middle discharge hopper 3 Chute 4 Extended chute 5 Regulator 6 Discharge chute support
The position of the feed hopper is above the mixing drum, with spray-proof rubber in the front, and the feed hopper outlet stretches into the inner chamber of the mixing drum opening and is fixed on the rack.
The position of the discharge hopper is below the mixing drum opening, with spray-proof rubber under it, and it is fixed on the rack. Concrete discharged from the mixing drum flows to the discharge chute through the discharge hopper.
Chute and extended chute are connected by hinges and are supported by the rack, which can swing within 180° horizontally. Expansion link can be moved in the drum body by rotating support drum body handle to change inclination angle between chute, extended chute and the ground. Under the action of deadweight, the concrete flows to the required located along the chute and extended chute.