1. RIPPING
Many contractors, when investigating a project, ask the question “Do I have to blast?”
That is the wrong question.
What we should investigate is
“Can I rip?”

2. RIPPING Physical characteristics which favor ripping are:
Fractures, faults and planes of weakness
Weathering

3. RIPPING Physical characteristics which favor ripping are:
Brittleness and crystalline structure

4. RIPPING Physical characteristics which favor ripping are:
High degree of stratification
or lamination
Large grain size
Stratification

5. Production depends on: Tractor speed Shank depth Number of shanks
RIPPING PRODUCTION
Production depends on:
Tractor speed
Shank depth
Number of shanks
2 shanks

6. Tractor speed RIPPING PRODUCTION
The tractor develops its greatest drawbar pull in first gear.
Generally speed should be between 1 and 1½ mph.

7. RIPPING PRODUCTION Shank depth
Rip at the maximum depth that penetration and traction allow.
Rip to a uniform depth if possible.
This is very important when scrapers are being used to haul the material.

8. RIPPING PRODUCTION Shank depth at the start of a pass.
Shank depth during the pass.

9. SHANKS
Number of shanks
3 shanks
Single shank

10. SHANKS

11. RIPPING PRODUCTION Number of shanks
The correct solution lies in trial and error.
Start with one in the center pocket.
If the material breaks satisfactorily
Try two, one in each outside pocket
Three may act as a rake and hold
slabs under the ripper.

12. RIPPING PRODUCTION ESTIMATES
Seismic-Velocity Method, most ripping-production charts are based on the relationship between rippability and the seismic wave velocity response of a material. Fig. 7.23

13. Ripping-production chart

14. RIPPING PRODUCTION ESTIMATES
A refraction seismograph can be used to determine the top of bedrock, and the thickness and strength of rock layers at or near the ground surface.

15. RIPPING PRODUCTION ESTIMATES
Raw seismograph data. It takes training to read and interpreter the data.

16. RIPPING EXERCISE
How many 370 hp dozers are needed to rip 8,000 bcy of trap rock in 8 hours. The rock has a seismic velocity of 6,200 ft per second. The conditions should be considered average. Efficiency will be a 45-minute working hour.

17. RIPPING EXERCISE Step 1. Check Capability 370-hp tractor
Trap rock, seismic velocity 6,200 ft/sec.
See Figure 7.18, which is for a 370-hp tractor.
Should be able to rip trap rock with seismic velocity up to 7,000 ft/sec.

18. RIPPING EXERCISE Step 2. Ideal Production 370-hp tractor Figure 7.23
Trap rock having a seismic velocity of 6,200 ft per second
Conditions should be considered average. (half way between the A and B on the chart)
500 bcy/hr

19. RIPPING EXERCISE
Step 3. Adjust for Igneous Rock with high seismic velocity
In igneous rock with seismic velocity of 8000 fps or higher for 850-hp tractors, and 6000 fps or higher for the 305 through 570-hp tractors , the production values shown on most charts should be reduced by 25%.

20. RIPPING EXERCISE
Step 3. Adjust for Igneous Rock with high seismic velocity
In igneous rock with seismic velocity of 6000 fps or higher reduce by 25%.
Trap rock having a seismic velocity of 6,200 ft per second
Reduce production by 25%

21. RIPPING EXERCISE  280 bcy/hr Step 4. Calculate Production

22. RIPPING EXERCISE  3.6  4 Step 5. Number of dozers
Number tractors =
 3.6  4
Must be an integer number

23. RIPPING
Heavy ripping will increase machine maintenance requirements by
30 to 40%.