Every freight wagon carrying coal from Jharia, iron ore from Daitari, or cement from Rajasthan rides on two bogies. The bogie is not a supporting character in the Indian Railways freight story — it is the lead.
The CASNUB 22HS is the most capable variant in the CASNUB family. It was developed by RDSO specifically to handle high-speed freight at heavy axle loads — a combination that most earlier bogie designs could not reliably achieve simultaneously.
At Loco Castings Private Limited (LCPL), we manufacture the CASNUB 22HS as a fully cast alloy steel bogie, from steel melt in our EAF furnace to dimensional inspection in our in-house mechanical lab, entirely at our foundry in Andal, West Bengal.
This article explains what the CASNUB 22HS is, what it does, who needs it, and why the way it is manufactured is as important as the specification itself.
What Is the CASNUB 22HS Bogie?
CASNUB stands for Cast Steel Narrow Jaw Bolster. The 22HS designation means:
- 22 — the maximum axle load category (22-tonne class)
- HS — High Speed
The CASNUB 22HS is a three-piece cast steel bogie comprising two side frames and a floating bolster, connected through a load-bearing and snubber spring system with friction shoe wedge dampers. It is an RDSO-designed component approved for use in Indian Railways freight wagon stock.
The three-piece design has been the workhorse of Indian Railways freight for over five decades — and the 22HS variant represents the highest-performance version of this proven architecture.
CASNUB 22HS Technical Specifications
| Parameter | CASNUB 22HS Specification |
| Maximum Axle Load | 22.9 tonnes |
| Maximum Speed | 100 km/h |
| Wheel Diameter | 1000 mm (new) |
| Wheelbase | 2000 mm |
| Journal Centres | 2260 mm |
| CP Height from RL (under tare) | 929 – 932 mm |
| Complete Bogie Weight | 5.4 tonnes |
| Bogie Type | 3-piece cast steel |
| Damping System | Friction shoe wedge |
| Design Authority | RDSO, Indian Railways |
Which Freight Wagons Use the CASNUB 22HS?
The CASNUB 22HS is the standard bogie for India’s highest-capacity and highest-speed freight wagon types:
- BOXN — Open Box wagon for coal and iron ore
- BCN / BCNA — Covered wagon for bagged goods
- BOBRN / BOBR — Bottom opening discharge wagon
- BTPN — Tank wagon for petroleum products
- BRN / BOBY / BOBYN — Various bulk mineral wagons
- BFK — Flat wagon for heavy equipment
The 22HS is favoured on routes where both speed and axle load are critical — including the Eastern and Western Dedicated Freight Corridors, where trains run at up to 100 km/h loaded.
Why the CASNUB 22HS Needs to Be Cast, Not Fabricated
This is the question that procurement managers should ask every supplier — and the answer shapes long-term maintenance costs.
A cast steel bogie is formed as a single continuous metal structure without welds. The side frames and bolster are poured as net-shape castings in alloy steel and machined to dimensional tolerances. The load path through a cast structure is continuous and predictable.
A fabricated bogie is welded from cut steel plates. Welded joints create stress concentration points under cyclic loading — exactly the loading regime a freight bogie experiences over hundreds of thousands of kilometres.
For a 22.9-tonne axle load running at 100 km/h over variable track, cast steel is not a preference — it is an engineering requirement. RDSO’s specifications for the CASNUB 22HS mandate cast alloy steel for the side frames and bolster for precisely this reason.
At LCPL, we use a 5-tonne Electric Arc Furnace with argon purging and ladle refining to control steel chemistry at the molecular level — phosphorus and sulphur below RDSO limits, grain structure refined for impact resistance. The result is a casting that does not just meet the specification on day one — it holds its mechanical properties across its entire service life.
How the CASNUB 22HS Suspension System Works
The three-piece bogie uses a friction wedge suspension — a brilliantly simple system that has proven itself over decades of heavy freight service.
The wedge sits at the junction of the bolster and the side frame column. Under load, the bolster pushes down on the wedge, which creates a lateral friction force against the side frame wear plate. This friction force acts as a damper — absorbing vertical oscillations and preventing hunting (self-excited lateral oscillations at speed).
The snubber springs in the spring nest maintain contact force on the wedge and control the stiffness of the damping system. The load bearing springs carry the full vertical load of the wagon body.
This system is self-adjusting within a range and requires no hydraulic components or electronic controls — which is why it remains the preferred design for high-volume freight applications in India.
The quality of the friction wedge itself matters significantly. LCPL manufactures HS wedges for CASNUB bogies to IS:276 Grade I specification — a detail that directly affects how consistently the damping system performs over time.
The CASNUB 22HS vs CASNUB 22NLB — When to Choose Which
The CASNUB 22NLB (Narrow Jaw Low profile Bolster) handles a maximum axle load of 20.32 tonnes at 80 km/h — a lower load and speed rating than the 22HS.
Choose the CASNUB 22HS when:
- The route includes Dedicated Freight Corridor segments where 100 km/h running is expected
- The wagon carries maximum permissible axle loads (coal, iron ore, heavy minerals)
- The operator is specifying new build wagons for long-term fleet development
Choose the CASNUB 22NLB when:
- The route is conventional track at lower average speeds
- The axle load is within the 20-tonne range
- Cost optimisation is a priority and DFC speed is not required
For a direct comparison including the LWLH 25, read our detailed guide: CASNUB 22HS vs 22NLB vs LWLH 25 — Which Bogie for Which Application.
LCPL’s CASNUB 22HS Manufacturing Process
Our manufacturing sequence at Andal:
- Steel chemistry design — alloy composition calculated for required RDSO mechanical properties
- EAF melting — 5-tonne electric arc furnace, temperature controlled to ±5°C
- Argon purging — dissolved gas removal from the melt
- Ladle refining — inclusion content control, sulphur and phosphorus reduction
- No-Bake moulding — chemically bonded sand for dimensional accuracy
- Pouring — controlled pour rate, gating system designed via 3D simulation
- Heat treatment — normalising and tempering to achieve required toughness
- Shot blasting — surface preparation, scale removal
- CNC machining — journal pocket, bolster wear surfaces, critical interfaces
- Inspection — spectrometry, UTS, Charpy impact, dimensional check
Every heat of steel is tested before pouring. Every bogie is dimensionally verified before despatch. There are no shortcuts in the process — because there are no shortcuts on the track.
Common Problems with CASNUB 22HS Bogies — and How Manufacturing Quality Prevents Them
Problem 1: Premature wear on bolster wear liners
Caused by: incorrect hardness profile of bolster casting, inconsistent wedge geometry Prevention: controlled heat treatment, wedge manufactured to IS:276 Grade I
Problem 2: Fatigue cracking at side frame pedestal
Caused by: high phosphorus/sulphur content in steel, poor casting grain structure Prevention: EAF with argon purging, spectrometry verification of every heat
Problem 3: Hunting instability at speed
Caused by: worn wedges, incorrect spring nest geometry, oversize journal tolerances Prevention: tight dimensional control on machined surfaces, wedge replacement at scheduled intervals
Problem 4: Corrosion and surface degradation
Caused by: inadequate surface preparation before painting Prevention: automated shot blasting to Sa 2.5 standard before any coating
The root of most field problems with cast bogies is not design failure — it is manufacturing variation that was not caught in the foundry. LCPL’s in-house testing infrastructure exists to catch exactly these issues before they become field problems.
Frequently Asked Questions — CASNUB 22HS Bogie
Q: What does the HS in CASNUB 22HS stand for? HS stands for High Speed. The CASNUB 22HS is rated for operation up to 100 km/h under full axle load, distinguishing it from the standard 22NLB which is rated to 80 km/h.
Q: What is the maximum axle load for the CASNUB 22HS? The maximum permissible axle load for the CASNUB 22HS is 22.9 tonnes, as specified by RDSO.
Q: Can the CASNUB 22HS run on the Dedicated Freight Corridor? Yes. The CASNUB 22HS is designed for 100 km/h operations and is suitable for DFC routes. The LWLH 25, rated to the same speed at a higher 25-tonne axle load, is the preferred bogie for new-build DFC wagons.
Q: What steel grade is used for the CASNUB 22HS side frames? RDSO specifies alloy steel meeting specific tensile strength, yield strength, elongation and impact requirements. LCPL uses EAF-processed alloy steel with verified chemistry to meet these parameters.
Q: How long does a CASNUB 22HS bogie last? With proper maintenance and timely wedge replacement, CASNUB bogies regularly achieve 20+ years of service life. The actual service life depends heavily on route conditions, axle loading, and maintenance schedule adherence.
Q: Does LCPL supply complete assembled CASNUB 22HS bogies or just castings? LCPL manufactures the cast steel components — side frames, bolsters, centre pivots and wedges. Contact sales@lococastings.in to discuss your specific supply requirement.
Q: What is the difference between CASNUB 22HS and CASNUB 22W? The 22W (Wide Jaw) was the earlier design. The 22HS replaced it with a narrower jaw profile, improved damping geometry, and high-speed certification. The 22HS has higher manufacturing tolerances than the 22W.