Journal bearing design criteria III / Oil galleries

Journal bearing design criteria III / Oil galleries

The main purpose of lubrication is to form an oil film between the two surfaces, which has sufficient thickness and is resistant to operating conditions. It aims to transform the mechanical friction that causes loss of energy into internal friction that occurs in the movement of oil particles in the oil film. This oil film layer can separate the shaft and bearing from each other and prevent the contact of the rough parts on their surfaces. If such an oil film is formed between the two surfaces, the friction here will be reduced to the friction between the oil layers. All lubricant particles will spread on metal surfaces and adhere to shaft and bearing surfaces with a performance dependent on the type, chemical structure and additives of the lubricant.

One of the factors affecting the formation of this oil film is the oil inlet and the oil gallery. One or multiple oils are supplied to bearings. The oil inlet opening must be in the appropriate geometric form (usually circular) and size; because the oil inlet must be sufficient not to prevent the flow of oil. For this purpose, the oil inlets are generally designed in the form of countersinks and have suitable roundings. In order to facilitate the formation of an oil wedge between the surfaces of the bearing and to provide a better distribution of the oil within the bearing, usually a number of oil galleries are opened by metal-cutting method. Oil galleries are also available in circumferential, helical, axial and open ended axial forms according to ISO 4378. In practice, the most commonly used types are circumferential and axial oil galleries.

Another purpose of oil galleries is to provide an oil chamber in the bearing and adequate oil flow for adequate cooling effect. It is possible to cool a hot bearing by using a simple shaped oil gallery to increase the oil flow. An axial oil gallery in the no-load part of the bearing is usually sufficient for the transfer of unidirectional loads. With this oil gallery, it is possible to achieve three times more oil flow in a bearing construction where there is only one oil hole. For loads with variable directions, circumferential oil gallery is a more suitable construction. However, the circumferential oil gallery also divides the bearing into two smaller bearings. This may reduce the total load carrying capacity of the bearing. In principle, it is more convenient to design the bearing so that the oil inlet and oil galleries are located in an area where there is no hydrodynamic pressure. By doing this, better oil flow will be achieved. Otherwise, the hydrodynamic oil pressure distribution will be significantly impaired, which reduces the load capacity of the bearing.

(References: Koç, E., Makina Elemanları Vol. 2., Akademisyen Bookstore, Tevrüz, T., Makine Elemanları ve Konstrüksiyon Örnekleri, Vol. 2., Çağlayan Bookstore, Kurbanoğlu, C., Makina Elemanları, Teori, Konstrüksiyon ve Problemler, Nobel Printing House, Durak, E., Industrial Lubrication Techniques Lecture Notes)
2.9.2019 16:30:00
Prof. Dr. Ertuğrul Durak     2256

Corner Posts - Last Added

Lubricants and biodiversity

Lubricants and biodiversity

Soil and water pollution caused as a result of production, transportation and consumption of lubricants throughout their life cycle and dispersion, leakage and spillage of ...

11.7.2020 09:35:00
Prof. Dr. Filiz Karaosmanoğlu     470
Journal bearing design criteria - VI Oil flow in bearing and leak flow at bearing edges

Journal bearing design criteria - VI Oil flow in bearing and leak flow at bearing edges

Sufficient amount of oil should enter the bearing in order to form a hydrodynamic oil layer with the bearing operation parameters (such as speed, lead, oil viscosity, bearing ...

13.3.2020 14:53:00
Prof. Dr. Ertuğrul Durak     1136
Lubricant packages

Lubricant packages

“The Lubricant Packaging Market 2019 In-Depth Analysis of Industry Growth Trends & Forecast up to 2024” indicates that plastic dominated over seventy percent of the ...

1.1.2020 11:01:00
Prof. Dr. Filiz Karaosmanoğlu     991
Journal bearing design criteria - V Bearing Width / Diameter (B/D) Ratio

Journal bearing design criteria - V Bearing Width / Diameter (B/D) Ratio

In journal bearings, bearing width (length) / bearing diameter (B/D) ratio is an important parameter for determining the load carrying capacity of the bearing. Usually the bearing ...

22.12.2019 17:13:00
Prof. Dr. Ertuğrul Durak     1858
Journal bearing design criteria IV - Bearing clearance

Journal bearing design criteria IV - Bearing clearance

Elements that carry power transmission elements such as gear wheel, belt and pulley or chain wheel mechanisms are called shafts. Shafts that assume this carrying task are ...

11.11.2019 12:02:00
Prof. Dr. Ertuğrul Durak     3624
Fossil resources: Environment and climate change

Fossil resources: Environment and climate change

The cost of providing welfare and comfort in our lives by using coal, oil, natural gas, and the products made from these fossil resources is very high for our planet. Therefore, ...

11.11.2019 11:56:00
Prof. Dr. Filiz Karaosmanoğlu     1634
Journal bearing design criteria III / Oil galleries

Journal bearing design criteria III / Oil galleries

The main purpose of lubrication is to form an oil film between the two surfaces, which has sufficient thickness and is resistant to operating conditions. It aims to transform the ...

2.9.2019 16:30:00
Prof. Dr. Ertuğrul Durak     2257
Journal bearing design criteria - II

Journal bearing design criteria - II

Bearing selection and design processes can be summarized as: -Selecting the optimum bearing type, -Calculating bearing sizes that will ensure safety, -Reviewing the performance ...

21.8.2019 16:33:00
Prof. Dr. Ertuğrul Durak     3380
Journal bearing design criteria - I

Journal bearing design criteria - I

In general, design is a production process that aims to find a solution for a specific function. Several alternative solutions can be offered to solve the problem in design ...

30.5.2019 11:52:00
Prof. Dr. Ertuğrul Durak     3356
Plant-oil-based lubricants - II

Plant-oil-based lubricants - II

Technical terms such as biodegradable, bio-based, environment-friendly, recyclable, renewable, non-toxic, green, etc. are frequently used in the industry as well as in our daily ...

1.4.2019 17:16:00
Prof. Dr. Ertuğrul Durak     3704