Wheel and Axles Of LHB Coach

 Wheel and Axles 

• Two brake disks (4), diameter 640 mm and width 110 mm. 
• Two wheel disc of tread dia 915 (New), 845 (worn) 

• Dynamic balancing 320rpm 
• Less that/equal to 50gm.m 
• Glue the needed weights. 

AXLE BEARINGS

• Taper roller cartridge type bearing 
• Pre-assembled unit. 
• Maintenance free- overhaul 1.2 million km. 
• Sensors for detecting speed 

DISC BRAKE SYSTEM 

• Axle mounted disc brake 
• Two discs per axle of dia640 
• Inbuilt slack adjuster in brake cylinders 
• 35mm brake pads 

SECONDARY SUSPENSION 

• Nest of flexi-coil springs inner and outer, rubber spring and secondary pad 
• Vertical dampers 
• Lateral dampers 
• Yaw dampers 
• Anti-roll bar 
• Anchor Links 

PRINCIPLES OF FORCE TRANSMISSION 

• Vertical forces: Body-secondary springs-bogie frameprimary springs/ball joint control arm-axles. 
• Lateral forces: Body-Secondary Springs-Bogie Frame-Ball Joint Control Arm-Axles. 
• Longitudinal traction efforts and braking powers: BodyTraction Centre-Traction Rods-Traction Lever-Bogie Frame-Control Arm-Axles. 

Curve Negotiation: An Articulated Control Arm (SGCI TO IS:1865) Is Connecting Axle Bearing And Side Frame Through Elastic Connection, Which Will Provide Flexibility Between Axle And Side Frame. 

Fiat Bogie Frame Fabrication: Sequence of Operations. 

• Stage- i: Fitting of top flange, bottom flange, web and 6 ribs. 
• Stage-ii: Fitting of control arm bracket, inside stiffener, brake head bracket, bkt for vertical damper. 
• Stage iii: Robotic welding of above items.(mfr. M/S IGM ROBOTER system as Austria) 
• Stage iv: Yaw damper assembly Bkt. & curve roll link Bkt. Tacking. 
• Stage v: Full welding of bogie frame on manipulator. 
• Stage vi: Flame straightening of side frame. 

SALIANT FEATURES - Wheel and Axles 

Speed limit: Up to 160KMPH without any modification & up to 200KMPH with minor modification 

Riding index for Chair car: VERTICAL - 2.75 & LATERAL - 2.5 

Comparison of salient features of fiat bogie against I.C.F. Bogie 

Wheel Slide Protection device: 

In LHB coach pneumatically controlled Disc brake system is used. During brake application, factors like variation of co-efficient of friction (due to composition of brake pads and disc) and adhesion between rail and wheels and various other factors may cause difference in RPM (rotation per minute) of axles on the same coach. This may lead to wheel skidding/ flat tyres. To prevent this, a Wheel Slide Protection (WSP) device is provided in these coaches. 

Main Components and their functions: 

Principle of working: The rotation of each axle is constantly measured and compared with a reference speed (The RPM of the fastest wheel of the coach) for that coach. In case there is a variation in RPM among the wheels, WSP automatically releases the brakes of the wheel with slower speed accordingly, so that the RPM of all the wheels become uniform. 

Working: The limit of variation of speed and acceleration are defined as threshold values. The Micro Computer constantly compares the signals from the speed sensor mounted on each axle with the reference speed. If the speed/ acceleration of any axle are crossing the present threshold values, it gives signal to the respective Rapid Discharge Valve to release the BC pressure accordingly, thus maintaining the speed/acceleration within the threshold level.