In Diesel, the duration between the time of injection and the time of ignition is called Delay Period.

What is the Delay period in CI engine?

The diesel engine is a compression ignition system. The injector injects the fuel into the cylinder and the fuel self-ignites due to a high temperature of compressed air. But the atomized fuel from the injector is considerably colder than compressed air in the cylinder. So, after injection, it takes some time for the fuel to reach the Self-Ignition Temperature (SIT). This period of time is the Delay period or Ignition lag.

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World’s leading construction equipment: Construction is a very large industry and there are many types of equipment that are used in the construction sector. Many large, as well as small machines, are used for building and structural construction, road construction, underwater, and other marine construction and power projects, etc. There are various things that are done in construction projects. For example, large amounts of earth digging and excavation, placement of building materials (eg: -bricks, concrete) compacting and leveling, dosing, grading, hauling, etc.

Top 10 World’s leading construction equipment OEM

1. Caterpillar

Caterpillar Inc. is an American corporation and major construction equipment manufacturer. They design, develop, engineer, manufacture and sell machinery, engines, financial products as well as insurance to customers through a worldwide dealer network. Caterpillar is a World’s leading in both construction equipment and mining equipment manufacturing. It also manufactures diesel and natural gas engines, industrial gas turbines, and diesel-electric engines. The Caterpillar’s headquarter is in Pieria, Illinois, United States.

2. Komatsu

Komatsu Limited is a Japanese multinational corporation. They are one of the top manufacturers in construction equipment. In addition to construction, they are into mining, military and industrial machines such as press machines, and thermoelectric generators. Komatsu is headquartered in Minto, Tokyo, Japan. Firstly Komatsu Corporation was established in 1921. Komatsu is the second major manufacturer in both ‘construction equipment and mining equipment’.

3. Volvo Construction Equipment

Volvo Construction Equipment is a leading company for construction machinery. They manufacture and market equipment for the construction and related industries. It is a subsidiary and business sector of the Volvo Group. Volvo CE’s products include hydraulic excavators, wheel loaders, graders, clay and asphalt compactors, pavers, backhoe loaders, skid steers, and milling machines. Volvo CE is headquartered in Brussels, Belgium

4. Hitachi Construction Equipment

Hitachi Construction Machinery is a company of Hitachi Group in Japan. Hitachi Construction Machinery (HCM) is a pioneer in the field of construction machinery and has manufacturing facilities in Europe, America, and Asia.

5. Liebherr

The Liebherr Group is one of the World’s leading construction equipment manufacturers based in Switzerland. It structures more than 100 companies into eleven divisions: Maritime Cranes, Mobile Cranes, Earthmoving, Mining, Tower Cranes, Concrete Technology, Aerospace, and Transportation Systems, Machine Tools and Automation Systems, Home Appliances, Components, and Hotels.

6. Sany Global

Sany is a Chinese MNC for heavy Equipment manufacturing. It is headquartered is in Changsha, Hunan China. It’s the sixth-largest heavy equipment manufacturer within the world.

7. Terex

Terex Corporation is a top manufacturer of lifting and material handling solutions. They manufacture for a variety of industries including construction, infrastructure, energy, mining, shipping, transportation, and utilities. Terex is an American company and its headquarter is in Westport, Connecticut, United States.

8. Doosan Infracore

Doosan Infracore is a South Korean company. Its headquarter is in Jung-gu, Seoul, South Korea. They produce excavators, loaders and diesel engines, ranging from compact to large-size machinery. Bobcat, USA is also a subsidiary of Doosan Infracore.

9. JCB

JCB is one of the top 10 manufacturers of construction equipment in the world. The headquarter is in Rocester, UK. It produces more than 300 types of construction machinery and industrial machines, including backhoe loaders, excavators, tractors and diesel engines. Simultaneously It has 22+ factories worldwide. Today, JCB has become one of the world’s top OEMs in industrial machinery. It deals with various industries like construction, agriculture, logistics, waste and recycling, power generation.

10. Kobelco

Kobelco Construction Machinery is today a leading OEM company of excavators and cranes. Kobelco Construction Machinery Company Limited, founded in 1999 and headquartered in Japan, is one of the Kobe Group’s nine business domains. The group, first founded in 1905, now employs around 40,000 workers worldwide. The main products and services provided by Kobelco Construction Machinery include road construction equipment, hydraulic excavators, mini excavators, wheel loaders, crawler cranes, wheel cranes, and other construction machines.

Top road construction equipment manufacturer

In this list Caterpillar again on top. Here is the list for road construction equipment manufacturers.

1. Caterpillar
2. Volvo
3. JCB
4. HAMM
5. Asphalt
6. Escort
7. Sany
8. LiuGong
9. ACE
10. Leeboy

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The basic function of a Gear coupling is to provide a mechanical connection between two rotating shafts. They use gear mesh for transmitting power and torque between the connected shafts. Hence, gear Coupling is a mechanical device that transmits torque between two shafts by using gears.

A gear coupling is very much considered a flexible coupling. It can transmit torque between two shafts that are not collinear or which have some misalignment.

The function of a Gear coupling to be a positive torque transmission coupling. It is suitable for horizontal assembly. However, the specially designed gear couplings are available for vertical assembly too. Moreover, It provides high torsional stiffness due to gears and therefore it is torsionally rigid coupling. Generally, the gear ratio is 1:1.

Type of gear coupling

Mostly there are two types of gear coupling in uses.

1. Flexible-flexible coupling (or flexible gear coupling).
2. Flexible-rigid coupling (or semi-flexible coupling).

Flexible Gear coupling: It consists of two hubs with external gears and two sleeves with internal gears. Both the hubs and sleeves are coupled with gear mesh and bolted with bolts.

A flexible gear coupling can use for all sort of application & accommodates all possible misalignments (angular, offset, axial or combination of all).

So, there is no additional force on machines, bearings, seals and shafts.

Semi-Flexible gear coupling: It consists of one flexible half likewise flexible coupling but another half will be fixed like flange coupling. And both the half will be coupled together with bolts.

Wherever there is less chance of misalignment one can use semi-flexible gear coupling. Thus, he can reduce the cost. Particularly Minimizing the misalignment means maximizing the life of coupling, machines, bearing, seals and shafts.

Specially designed gear teeth

If the teeth of gears are simply straight, there will be more wear and tear on gear profile. Because under misalignment condition the teeth contacts will be minimum. And also there will be excessive play. Because of this play and minimum teeth contact between the hub and sleeve, teeth edge will get damaged and reduce the life of the coupling.

Therefore, crown teeth hubs are using instead of straight teeth hubs. Crown teeth have curvature on the flank which increases the contact area between hub and sleeve, reduces edge pressure and hence, increases the life.

Following are the points to remember during installation.

Some gear coupling does not get a chance at a decent life due to their installation.

Hub and Sleeve: Higher speed application should have adequate interference fit to offset centrifugal force effects on the shaft. But If the contact pressure between the shaft and hub is excessive due to the interference fit, it may lead to hub failure.

Key and keyways fit: Keyways should have a proper radius to reduce the risk of fatigue cracking. Also, the key length should be measured to minimize coupling imbalance.

Hub bore: Ensure hub bore must be concentric to minimize hub run-out.

Hub installation: Choose proper heating method so that the hub’s material properties do not compromise. Also, take care of the heating temperature for interference fit so the hub can slide easily over the shaft. Never use the hammer to install or remove the hub as it can damage the gears, bearing etc.

Correct coupling gap: If the floating shafts have a small gap, the shafts may impact each other and get damaged.

Proper sealing: Ensure proper gasket and O-ring to retain the lubricants in the coupling.

Alignment: Alignment for the components must be within the limit.

Maintenance

Lubrication is the only main part of maintenance for gear coupling. Lubricants reduce the friction between the teeth as they slide each other. There is relative motion between teeth due to misalignment. This motion is oscillatory, low amplitude and high in frequency. This causes wear and tear and heat generation. But with the good lubrication, it can minimize.

Generally, the manufacturer recommends regreasing in every 12 months but completely depends on the uses and condition. Hand packing method is used for regreasing in annual maintenance.

This is all about the function of a gear coupling.

Thank You

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