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Section III Basic structure of SDTW 0.8T excavators mechanical system
1 Power system
The SDTW 0.8T excavator is equipped with single-cylinder air-cooling diesel engine.
2 Drive system
The SDTW 0.8T excavator's drive system transfers the output power from the diesel engine, through the hydraulic
system to the work equipment, swing mechanism and traveling mechanism.
3 Swing mechanism
The Swing mechanism turns the work equipment and upper rotary in left and right directions, to allow excavating
and unloading. The SDTW 0.8T excavator’s swing mechanism fixes the rotary table onto the frame allowing it to
swing without any inclining risk. The machine is equipped with slewing supports and a slewing drive (power of
turntable slewing), known as the swing mechanism.
3.1 Slewing support
The SDTW 0.8T excavator has its rotary table supported with a rolling bearing, allowing the swinging of
upper rotary.
3.2 Rotary drive
The SDTW 0.8T excavator adopts a direct drive system. Namely, the output shaft of the low-speed
high-torque hydraulic motor is mounted with a driving pinion which meshes with the slewing gear ring.
4 Traveling mechanism
The Traveling mechanism supports the complete weight of excavator and drives it to operate.
The SDTW 0.8T excavator has a crawler traveling mechanism similar to other crawlers, with one hydraulic motor
driving one track. This excavator adopts a low-speed high-torque motor. When two hydraulic motors run in the
same direction, this machine goes straight forward; when one motor is engaged and the other is braked, the
excavator steers around the braked track; when the two motors run in reverse, the excavator rotates in situ.
Each part of traveling mechanism is mounted on an integral traveling frame. Pressurized oil from the hydraulic
pump goes through the multi-directional valve in the central swing joint, into the hydraulic traveling motor that
changes the pressure energy into output torque, which then goes to the sprocket to drive the excavator.
The SDTW 0.8T excavator’s sprockets are integrally casted and able to correctly engage with the track, to achieve
a balanced drive. Sprockets located at the rear of the excavator, shorten the tensioner and reduce track abrasion,
wear and power consumption.
5 Work equipment
The hydraulic excavator can use multiple work implements.
The excavator boom, arm and bucket are articulated with each other, as shown in figure and swing around their
articulated points respectively with the aid of the hydraulic cylinder.
5.1 Boom
As the main component of the excavator, the integrated skewed boom is adopted on to the SDTW 0.8T excavator,
allowing the excavator to dip deeper and to achieve a lower unloading depth.
