W26.60-1080-06
Hydropneumatic drive control in the gearbox 715.5
5 Transmitter device
6 Gear control cylinder
7 Selection cylinder - engage
8 Equalizing tank
Hydropneumatic drive gearbox replaces conventional shift lever gearbox; it adds comfort and safety for the control maneuvers. The absence of mechanical gear shift and shifter rods allows to obtain clearance for structures behind the driver's cab. In addition, under very difficult conditions for maneuvering, it prevents chassis strokes and vibrations from being transmitted to the driver's cab, through the gearshift. Instead of rods and control levers, the hydraulic system is used. Thus, it avoids the jumps from one gear to another coming from relative movements between the driver's cab and chassis.
The hydro-pneumatic drive (HPS) is composed of a hydraulic system to engage gears and an electropneumatic system to switch the additional group (divider) and the multiplier group (degrees).
The main components of the hydraulic control system are:
The hydraulic transmitter device with oil sump and equalizing tank
Hydraulic pipes and hoses
The hydraulic control cylinder for gears
The selection hydraulic control cylinder
The transformation of the mechanical movement in the gearshift into hydraulic movement, whose retention, as well as the self-centering of the gearshift to perform the initial assembly, maintenance or repairs are performed by the hydraulic transmitter device in the driver's cab.
The shift hydraulic system works with two hydraulic circuits of double effect, independent among themselves. One of the hydraulic circuits is responsible for selecting the gear, whereas the other is in charge of selecting the engage. According to the movement of the gearshift (driver's intention) one of these two hydraulic circuits transmits hydraulic pressure and oil flow from the transmission device until the control cylinders (receiver cylinders) of the gear or engage.
The hydraulic oil is subjected to high requests and transmits the circuit pressures up to 100 bars. For this reason, it should not be mixed under any circumstances (with minerals oils), as this procedure causes total damage of the system.