The various bogie versions developed are as under:
- CASNUB -22W
- CASNUB -22W (Retrofitted)
- CASNUB -22W(M)
- CASNUB -22NL
- CASNUB NLM
- CASNUB -22NLB
- CASNUB -22HS
The Casnub bogie assembly consists of the following components:
- Wheelset with Cartridge Bearing
- Adapter, retainer bolt & side frame key assembly.
- Side frames with friction plates
- Bolster with wear liners
- Spring plank, fit bolts & rivets
- Load bearing springs and snubber springs.
- Friction shoe wedges
- Centre pivot arrangement comprising of Centre pivot top, Centre pivot bottom, Centre pivot pin, Centre pivot retainer & locking arrangement
- Side Bearers
- Elastomeric Pad
- Bogie Brake Gear
- Brake Beam
CASNUB bogie – top view:
These bogies are now used in the following wagons:-
- “ wide jaw” category.
- The adapter is not provided with elastomeric pad (EM Pad) where the later versions are provided with EM pad
- The shape of the bolster at the bottom is straight and center pivot, known as IRS type, is fitted with the bolster. A simple straight pin is used to connect bolster with the body of the wagon through center pivot.
- The side bearer is of “clearance type”. A pair of rollers is used with each bogie maintaining a nominal clearance with the body. The load is transferred to bolster only through center pivot but not through side bearer while in motion on a straight track. Side bearer shares vertical load only during motion on curved track.
The brake beam used in this version is known as “pocket type” or “sliding type”. The brake head is an integral part of the brake beam and slides in the pocket provided in the side frame.
The disadvantages of this bogie are:
- Higher wheel wear
- Replacement of brake beam requires removal of wheelset
- Low stability as significant vertical load not shared by side bearer
Two types of 22 W:
- Integral type center pivot
- Non-integral type center pivot
This falls under wide jaw category same as a 22W version. The major difference in the side frame as compared to 22W is a provision of negative camber (sag at the middle of the side frame) to take care of maintaining same buffer height while using EM pad. EM pad has been introduced along with the adapter to reduce the incidence of higher wheel wear as experienced with the 22W version.
The bolster used with this bogie is same as that of 22W version. The only difference is that “spherical type” center pivot is fitted with this bolster. Pin with the castle nut and split pin is used to connect the bolster with the body of the wagon through the center pivot.
The side bearer used with this version is metal bonded EM pad maintaining constant contact with the body. This improves the stability of the wagon as the compared 22W version.
Hanger type Brake beam assembled with separate brake head through spring-loaded brake shoe adjuster is used with this version. This has the advantage in replacing brake beam without running out of the wheelset. But this design has suffered set back due problem of dropping of brake beam and grazing of brake components. This design is discontinued in the later versions of the bogie.
This is basically 22W version incorporated with some of the better design aspects of 22W(M).
The main differences with 22W are:
- Use of elastomeric pad with the adapter
- Use of constant contact metal bonded elastomeric pad inside bearer housing
- To accommodate elastomeric pad and to maintain buffer height, the height of the adapter has been reduced. However, it is not possible to use higher diameter wheelset to maintain the buffer height. Wheel below the diameter of 956 mm is to be used with this version.
- “Narrow jaw” category. The side frame is modified to accommodate elastomeric pad similar to 22W(M) version and pocket to accommodate sliding type brake beam hanger similar to 22W version. The side bearer, center pivot, bolster are similar to 22W(M) version.
- Centre pivot pin is locked by shackle lock unlike castle nut used in 22W(M) version.
- The adapter used with this version is of smaller size to suit to narrow jaw opening of the side frame.
This version is similar to 22NL version, except for bolster. The shape of the bolster is “fish belly” at the center to reduce the weight of bogie. However, only a marginal weight reduction compared to NL type has been possible.
- similar to NLB version in relation to dimensions of the components.
- The only difference is a change in the material of the side frame and bolster. The equivalent carbon % of the side frame and bolster in NL/NLB is 0.85%. This has resulted in a reduction of weight of the bogie compared to NL version.
- The weight of the NLM version bogie is 5.125 ton whereas the weight of NL version is 5.5 ton.
- The CASNUB –22HS bogie has been developed for high- speed operation with the maximum permitted to speed up to 100 Kmph. The side frame, elastomeric pad, center pivot, center pivot lock, adapter are similar to NLB version.
- The bolster is mostly same as NLB type except for outer gib opening and higher diameter spigot for the spring seat. The outer gib opening has been increased to 241 mm from 234 mm as in case of NLB type.
- The side bearer used with this version is spring loaded constant contact type.
The spring nest in the secondary suspension used with this version is different to that of other versions. The spring combination in the different version of the bogies are given below:
Each spring-nest arrangement should be as follows: