Two-Bar Earth-Cutting Machine 2BTDT
Abstract Generated abstract
The article presents the design rationale and main characteristics of the 2BTDT two-bar earth-cutting machine, developed to reduce maneuvering operations when preparing frozen ground for excavation. Drawing on operating experience and calculations for the URMG-60 single-bar installation, it estimates cutting power requirements and justifies the use of a 100 hp KDM-100 engine for simultaneous cutting of two slots. The paper describes the machine’s principal modifications, including the second bar suspension and drive, redesigned lifting frame, and kinematic scheme providing multiple working speeds and cutting-chain speeds to adapt operation to varying soil hardness.
Full Text
PROCEEDINGS
OF THE TOMSK ORDER OF THE RED BANNER OF LABOR POLYTECHNIC
INSTITUTE named after S. M. KIROV
Volume 129 1965
I. G. BASOV
TWO-BAR EARTH-CUTTING MACHINE 2BTDT
(Presented by the Department of Mining Machines and Mine Transport)
The preparation of frozen ground for excavation by means of single-bar earth-cutting installations is accompanied by a comparatively large volume of maneuvering operations. In this connection, a number of construction organizations have recently begun to create two-bar machines, which cut two slots in frozen ground in a single pass. These installations are manufactured on the basis of tractors and trench excavators. They operate under the most varied regimes of cutting frozen soils. Some deepen and hold the bars in the required position under the action of their own weight and in so doing provide low productivity; others excavate the soil while combining the processes of cutting the soil and moving the machine, but have excessively high feeds (minimum 1 m/min).
Taking the above into account, the staff of the Department of Mining Machines and Mine Transport developed, on the basis of the TDT-60 skidder tractor and the units of slot-cutting machines, the two-bar earth-cutting installation 2BTDT with the following technical characteristics:
| Characteristic | Value |
|---|---|
| engine power, hp | 100; |
| maximum depth of cutting slots in the ground, m: | |
| a) with bar length 2 m | 1.3; |
| b) with bar length 2.8 m | 2.1; |
| number of cutting slots | 2; |
| distance between slots, mm | 700; |
| width of the cutting slot, mm | 140; |
| speed of movement of the cutting chain, m/sec | 0.79; 1.55; 3.06; |
| operating travel speeds (40 speeds) vary within, m/min | 0.246—6.9; |
| maneuvering travel speeds, km/hr | 0.88—6.15; |
| average hourly technical productivity, m/hr | 180—240; |
| overall dimensions, mm: | |
| length × width × height | 8300×2370×2700; |
| weight, t | 11.5. |
Experience in operating the URMG-60 single-bar earth-cutting installation [1] has shown that, at a cutting-chain speed of 1.55 and 3.06 m and when cutting is combined with movement of the machine, the rate of cutting a slot 1.3 m deep in frozen ground, in the case of full engine load, is 1.0—1.5 m/min. At the same time, as calculations show, the average value of the cutting depth (chip thickness) amounts to
0.6–1.8 cm (Fig. 1), and the power consumption for cutting is 22.0–39.0 hp (Fig. 2), or 36.5–65% of the installed engine power.
If it is assumed that a two-bar earth-cutting unit must provide the same productivity per bar as the URMG-60, then the power expended by it on cutting alone will be 30.0–51.0 hp (Fig. 2). In this case the installed engine power must be no less than 80–82 hp. In this connection, the 2BTDT earth-cutting machine provides for installation of a KDM-100 engine with a power of 100 hp.
Fig. 1. Dependence of the cutting depth of a single cutter on feed speed.
1, 2—at chain travel speeds of 1.55 m/sec and 3.06 m/sec, respectively.
The principal layouts of the 2BTDT and URMG-60 earth-cutting units [1] do not differ in any way.
The design differences of these machines are as follows. The 2BTDT unit has two bars; in connection with this, a suspension assembly and drive for the second bar from the cutting part of a KMP-type coal-cutting machine have been developed. The A-shaped frame for fastening with a hydraulic jack for raising and lowering the bars has been redesigned.
The kinematic diagram of the 2BTDT unit is shown in Fig. 3. The transfer gearbox has gear ratios of 1.24 and 2.44, depending on the position of toothed wheel 3. With the aid of cardan shafts 8 and 16, rotation from the transfer gearbox is transmitted to the demultiplier and the cutting part of the unit.
In this case the ratchet mechanism of the demultiplier is disengaged by eliminating the eccentricity of the crank pin.
The combination of a two-speed transfer gearbox, a four-speed ratchet demultiplier, a five-speed tractor gearbox, and a two-speed reducer for the cutting unit makes it possible to have 40 different working travel speeds of the installation, 12 maneuvering speeds, and three speeds of motion of the cutting chain. This enables the operator of the installation, depending on the hardness of the soil being excavated, to select regimes that ensure maximum utilization of the drive power.
Fig. 3. Kinematic diagram of the 2BTDG installation.
The cutting chain of the installation is driven by cardan shaft 16 through a two-speed reducer. Disengagement of the cutting chain and switching of its travel speeds are carried out by means of toothed clutch 21. If it is moved to the right, then transmission of motion from cardan shaft 16 will go through gear wheels 17—18—22—23 to sprocket 24 of the cutting chain. With clutch 21 in the extreme left position, sprocket 24 is driven through wheels 19—20—22—23.
A third speed of motion of the cutting chain, different from the preceding two, can be obtained by changing the rotational speed of cardan shaft 16 by means of the transfer gearbox.
The 2BTDT installation can be widely used in various kinds of earth-moving construction work carried out in winter.
REFERENCES
- O. D. Alimov, I. G. Basov, Z. M. Pratusevich. Cutting frozen soil with the URMG-60 installation. Tomsk, 1963.