Lubrication, Maintenance, and Total Cost
From lubricant selection to total cost of ownership: determining whether to use grease or oil, calculating relubrication intervals, maintaining roller guides, and assessing the total cost of ownership (TCO) of a drive train.
5 units · approx. 36 minutes total · Step 1 of 7
Getting Started
This module covers lubrication, maintenance, and the total cost of ownership of a drive train—from choosing between grease and oil to selecting the appropriate viscosity grade and calculating relubrication intervals for rolling bearings. You will learn how the dn value, temperature, load, and environment affect lubrication intervals, and what a structured maintenance plan for roller guides looks like.
The course concludes with a discussion of the total cost of ownership: why, in continuous operation, it is efficiency—rather than the purchase price—that determines the costs—and what this means for procurement and supplier consolidation. Calculation exercises on relubrication intervals and the total cost of ownership, eight flashcards, a case study from the procurement department, and a self-test at the end bring the theory to life.
Learning Objectives – After completing this module, you will be able to:
- determine the appropriate choice between grease and oil for a given application based on speed (dn value), temperature, and sealing;
- roughly classify the appropriate ISO VG viscosity grade for gearboxes and rolling bearings;
- Calculate a relubrication interval for a grease-lubricated rolling bearing using the approximate formula;
- create a maintenance and lubrication schedule for roller guides and avoid typical lubrication errors;
- Classify the TCO cost categories of a powertrain and the cost categories of a procurement beyond the unit price.
Learning units
Five short learning units (6–8 minutes) with learning objectives, examples, and knowledge checks—standalone learning content for this module, maintained independently of the website’s guides. Progress is saved locally in this browser.
0 of 5 units
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- Unit 1 of 5
Grease or Oil?
approx. 6 minutes
Open - Unit 2 of 5
Viscosity and Grades
approx. 7 minutes
Open - Unit 3 of 5
Lubrication Intervals and Relubrication Periods
approx. 8 minutes
Open - Unit 4 of 5
Maintaining Roller Guides
approx. 7 minutes
Open - Unit 5 of 5
Total Cost and Procurement
approx. 8 minutes
Open
Calculation Exercise 1: Relubrication Interval
A deep groove ball bearing 6309 (bore diameter d = 45 mm) operates at n = 1,800 min⁻¹. According to the approximation formula from the guide, the basic interval (without correction factors) is t_grund ≈ 9,790 operating hours. The load and operating environment are not critical (f_L = f_U = 1.0), but the bearing temperature is around 85 °C (f_T = 0.5).
Calculate the relubrication interval t_f in operating hours and the calendar time in years for operation at 2,080 hours per year (8 h/day, 5 days/week).
For further reading: Calculating relubrication intervals (opens in a new tab)
Calculation Exercise 2: Total Cost of Ownership (TCO)
A drive delivers 11 kW of mechanical output power at 6,000 operating hours per year, either with a worm gearbox (η = 70 %) or a planetary gearbox (η = 96 %)—using the same IE3 motor (η ≈ 91.4%, assumed to be the same for both variants for simplicity; in reality, the worm gearbox variant requires a larger motor). In the example provided in this learning unit, the annual energy consumption is 103,157 kWh with the worm gearbox and 75,219 kWh with the planetary gearbox.
Calculate (a) by what percentage the energy consumption of the worm gearbox is higher, and (b) the resulting additional CO₂ emissions in metric tons over 10 years (emission factor 0.344 kg CO₂/kWh, German electricity mix in 2025, Federal Environment Agency).
Flashcards: Lubrication and Maintenance Terms
Eight technical terms from the glossary—click on the card (or press Enter or the spacebar) to see the definition.
Flashcards
Tap to see the definition.
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- Tribology
- The science of friction, wear, and lubrication on surfaces in relative motion—the scientific basis for selecting lubricants, surface coatings, and bearing designs. Source: Glossary “Tribology”
- L10 service life
- The L10 service life is the nominal service life (in kilometers of travel) that at least 90% of all guides in a series achieve without material fatigue. It relates the dynamic load rating C to the equivalent operating load P and is the standard parameter for the service life design of linear guides and rolling bearings. Source: Glossary “L10 service life”
- Pitting
- Pitting refers to small, shell-shaped indentations on the tooth flank caused by rolling fatigue. This is caused by excessive Hertzian contact pressure, which, due to alternating compressive and tensile stresses beneath the surface, ultimately leads to cracking and material spalling. Source: Glossary “Pitting”
- Dynamic load rating
- The dynamic load rating C is the load at which a guide or bearing series achieves a defined nominal service life (typically 100 km of travel). It is the key parameter in the L10 service life calculation: The higher the C value, the longer the service life at a given operating load. Source: Glossary “Dynamic load rating”
- Rolling element
- Rolling elements are the components that roll between two raceways in guides and bearings. They transmit the load and minimize friction. Balls provide point contact for high speeds; rollers provide line contact for higher load-carrying capacity. Source: Glossary “Rolling element”
- Line contact
- In line contact, a cylindrical roller contacts the raceway along a straight line rather than at a single point. The load is distributed over a larger area—resulting in higher load-carrying capacity, lower contact pressure, and greater stiffness compared to the point contact of a ball. Source: Glossary “Line contact”
- Roller recirculation
- In a roller recirculation system, the rolling elements circulate in a closed path within the carriage. This design allows for a theoretically unlimited travel distance—in contrast to non-circulating guides (e.g., crossed-roller guides), where the stroke is limited by the cage length. Source: Glossary “Roller recirculation”
- Cage positive guidance
- Cage positive guidance is a mechanical method of synchronizing the rolling element cage—typically via a rack and pinion. It prevents unwanted cage movement, which can occur particularly under high dynamic loads, vibrations, or frequent changes in direction. Source: Glossary “Cage positive guidance”
All cards in this unit have been shown. The unknown ones are now in the review stack.
Case Study: Purchasing Asks—Is There a Cheaper Supplier?
A customer operates a pump with a mechanical output of 11 kW in continuous operation (6,000 operating hours per year), with a planned service life of 10 Jahre. Currently, a planetary gearbox is installed. The purchasing department has received a significantly lower quote for a worm gearbox from a new supplier and would like to switch to this supplier based solely on the lower purchase price.
Key Questions
- Given this operating profile, what percentage of the total cost of ownership (TCO) does the purchase price typically account for, and what percentage is accounted for by energy costs?
- How does the annual energy consumption change if a worm gearbox (η = 70%) is used instead of a planetary gearbox (η = 96%)?
- What would you recommend to the purchasing department—and what information is still needed to make a fully informed decision?
View Worked Solution
1. In continuous operation, the purchase price typically accounts for only a fraction of the TCO (guideline: components 3–8%, approximately 5–12% including installation), whereas energy costs account for 70–90%. With this operating profile, a lower purchase price says very little about the total cost of ownership.
2. In the example provided in this learning unit (IE3 motor, 11 kW, η ≈ 91.4 %, 6,000 h/year), the worm gearbox consumes about 37% more electrical energy per year than the planetary gearbox (103,157 kWh instead of 75,219 kWh) and emits about 96 metric tons more CO₂ (355 t instead of 259 t, emission factor 0.344 kg CO₂/kWh, German electricity mix in 2025). For simplicity, motor efficiency is assumed to be the same for both variants (IE3, 91.4 %); in reality, the worm gear variant requires a larger motor.
3. Recommendation: Compare the total cost of ownership (TCO) over the planned service life rather than just the purchase price—the difference in efficiency generally far outweighs the initial cost advantage of a worm gearbox in continuous operation. Missing information: the actual operating hours per year, the load profile (continuous operation or only occasional use), and whether self-locking is required at all—in which case a worm gearbox could still be the right choice despite the energy costs. A simple unit price comparison overlooks the largest cost factor.
Technical basis exclusively: Calculating TCO in the powertrain (opens in a new tab)
Self-test
10 questions about this module—immediate feedback with explanations and source links. The module is considered complete if you score 7 out of 10 points or higher.
Self-test
10 questions for this module. You see right after each answer whether it was correct.
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Before each answer, you state how confident you feel. This helps distinguish knowledge gaps from uncertainty. It has no effect on the score.
Question 1 of 10
Advanced Topics (optional)
The six guide articles in this module, in case you’d like to delve deeper. Reading them is not required for the learning units and self-test in this module.
6 Min. reading time
Determining the Correct Lubrication Intervals (opens in a new tab)7 Min. reading time
Viscosity: Choosing the Right Class (opens in a new tab)6 Min. reading time
Calculate relubrication intervals (opens in a new tab)7 Min. reading time
Roller Guide Maintenance & Lubrication (opens in a new tab)7 Min. reading time
Calculating TCO in the Powertrain (opens in a new tab)9 Min. reading time
Curriculum v0.1 (Beta) · As of 17.09.2026 · content carefully prepared and reviewed – final sign-off to follow