Practical Example of Modification of a Gearbox Lubrication System

Round 1

Reviewer 1 Report

1. The abstract describes the research process step by step, but does not disclose the features of the proposed method. The Introduction chapter is full of lengthy discussions about the benefits of lubrication and the types of surface damage. These facts are widely known. If the purpose of the work is to propose a new lubrication method, then it was necessary to analyze the existing methods, their advantages and disadvantages.
2. It is necessary to clarify the difference between the terms wading and immersion, String 19: …in the body of gearbox…, string 80: …But the casing design… Body or casing?
3. The article must be carefully read. For example, String 68: …by Wang et al [7].Shi et al. [eight]…
4. It is necessary to clarify: is the damage of the bevel gear of the first stage caused not only by poor lubrication, but by poor-quality adjustment by special mechanism? Bevel gears needs precise set up and elaborated tune-up before work under load. 
5. Point 3.1 should be separated into a detached chapter. These are not results and discussion, but a description of the proposed system.
6. Chapter 4 "Conclusions" does not contain numerical values ​​for the targets. The conclusions are declarative. How has the durability of the gearbox been improved?

Author Response

The authors thank for the comments that have improved the quality of the manuscript. We tried to incorporate the comments as best as we could.

Author Response File: Author Response.pdf

Reviewer 2 Report

1. Page 3, line 144: Is it a straight or spiral bevel gear pair?
2.  Page 5, line 165: “…bevel gears with helical gearing.” Probably, it means spiral bevel gear.
3.  Page 6, lines 206-207: “The strength analysis was performed based on the parameters of the bevel gear pair with adequate method of loading and the required service life.” Which calculation method was used?
4.  “Figure 11. Gearing surface temperatures during dip lubrication.” What it means “gearing surface temperature”? Probably, it is the bulk temperature of the gear. For the gear failure is more important the maximum temperature of the tooth surface.
5.  What was the tooth surface roughness of the spiral bevel gear?
6.  What was the increase in the gearbox service life?

Author Response

The authors thank for the comments that have improved the quality of the manuscript. We tried to incorporate the comments as best as we could.

Author Response File: Author Response.pdf

Reviewer 3 Report

Thank you for the paper and the detailed description of the initial situation. 

Unfortunately, the scientific background is missing. The injection system is state of the art and does not contain any innovations. The damage that occurred at the bevel gear stage resulted from insufficient lubrication, as you stated. This is also shown by the damage figures in your paper. There, scuffing is clearly visible. However, there is no recalculation with regard to the scuffing load carrying capacity, nor is there any assessment of the scuffing load carrying capacity of the oil used. I wonder why the oil level was not simply raised so that the bevel gear stage is lubricated according to the state of the art? Thus, there would no longer be any deficient lubrication and, with the appropriate load carrying capacity of the gear oil, scuffing could already be avoided. Raising the oil level might therefore be sufficient to prevent the damages. However, there are no tests for this. Furthermore, there is no information on which gear damage occurred first, so that it can be assessed whether pitting or scuffing occurred first. Based on this, targeted optimization of the gear can then be carried out. Furthermore, measurements of the gear temperature are shown. Were bulk temperatures or surface temperatures measured here? Where and how were the measurements taken? From a scientific point of view, this would be important to know in order to be able to interpret the results shown in figure 10, 11 and 12. 

Furthermore, the facts are not considered in full. E.g. lines 222 to 224: The choice of oil type and in particular the additives depends, among other things, on the contact stresses occurring in the tooth contact. For example, oils of class API GL-5 are recommended for highly loaded hypoid gears. There is also no information about the classification of the gear oil you are using. Furthermore, the statements should always be backed up with sources. E.g. chapter 2.3. the statements in the first paragraphs are not backed up by any sources or investigations on your part.

 

Further notes:
- After names I would recommend to always indicate the source. For example, lines 71 and 74.
- Line 82: Torque does not occur in the tooth contact, these are contact stresses.
- Line 179: v=75m.min-1 v = 75 min-1
- Line 190: dot missing

Author Response

The authors thank for the comments that have improved the quality of the manuscript. We tried to incorporate the comments as best as we could.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

The corrections are accepted.

Author Response

Authors want to express gratitude that the revised manuscript adequately accomplished all of your expectations. And authors also want to thank for constructive criticism, which made the final manuscript more precise work of science.  

Author Response File: Author Response.pdf

Reviewer 3 Report

Thank you very much for the revision of your paper and especially for the addition of the investigations with increased oil level. However, there is still one point of criticism. You give torque and temperature measurements, but you do not show the experimental setup, measuring equipment used, nor do you give measurement inaccuracies. Thus, an evaluation of the quality of the measurement results and the findings derived from them is not possible. I would recommend adding this.

Author Response

The authors thank for the comments that have improved the quality of the manuscript. We tried to incorporate the comments as best as we could.

Required infirmation regarding the experimental setup, used measuring equipment and measurement inaccuracy were added to the manuscript.

Author Response File: Author Response.pdf

Round 3

Reviewer 3 Report

Thank you for your adjustments to the paper

One small note: line 592 is missing the figure reference.

 

Author Response

The authors want to thank very much for all comments. As authors, we did not see the missing reference to the figure in line 592, which was added. Once again, thank you very much. 

Author Response File: Author Response.pdf