Cast-iron “pot” sleepers: Which configuration correctly describes the arrangement of bowls (pots) and tie bars in pot-type sleepers?
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AA number of bowls connected together with a single tie bar
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BTwo bowls placed under each rail and connected together with a tie bar
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CTwo bowls placed under two rails and one between the rails
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DNone of these
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EOne bowl per sleeper with twin tie bars
Answer
Correct Answer: Two bowls placed under each rail and connected together with a tie bar
Explanation
Introduction / Context:Before widespread adoption of concrete sleepers, many systems used cast-iron “pot” sleepers on ballasted track. Understanding their physical arrangement helps in recognizing historic track forms and their limitations.
Given Data / Assumptions:
- Pot (bowl) elements made of cast iron.
- Tie bar connects individual pots to maintain gauge.
Concept / Approach:Pot sleepers typically consist of two separate cast-iron pots placed beneath the two rails. A tie bar connects them to preserve the gauge and transmit loads, while packing is done under each pot.
Step-by-Step Solution:
Identify how many pots per rail are used.Recognize tie bar function—holding gauge between the two rail supports.Select the configuration: two bowls under each rail, joined by a tie bar.Verification / Alternative check:Historic track diagrams show two pots aligned under the rail seats with a transverse tie bar.
Why Other Options Are Wrong:
- Multiple bowls chained by one tie bar: Not the standard pot sleeper arrangement.
- Two bowls plus one central: Not a recognized conventional configuration.
- Single bowl with twin bars: Does not provide stable two-rail support.
Common Pitfalls:
- Confusing pot sleepers with CST-9 and other cast-iron sleeper types with different geometry.
Final Answer:Two bowls placed under each rail and connected together with a tie bar