Taita - Control Tables

The control tables for Taita in 1982, before the loop and other structures were removed.

The control tables were updated in 1982 and the handsketch in 1983.








Taita Track Circuits


Taita track circuits







Taita Locking



Released By Relays
No Normal Reverse Normal - R Reciprocal Normal N/R Lock) No
21 75.78 25.28.31

21
23



23
24



24
25 (77 or 75R) (132 or 75R or 82R) . 127 . (161 . 162R or 75 or 74) .(134 or 75 or 84) . (77 or 74R or 75) .(129 or 78 or 75R) (27 or 74 or 75N) 21
25
26 75 . 124 . 125 . 126. 127 . (133 or 74 . 84R or 83) (134 or 74.84R or 74R.84)


26
27 126.127.79. (134 or 84R) . (132 or 82R or 77) . (129 or 77).(133 or 83 or 84R)


27
28 82 . 132 . (129 or 78) (133 or 83R or 78R)
21
28
29 129 . (132 or 82) 79

29
30



30
31 82.83.132.133
21
31
32 83.132.133 82

32
33



33
34 133 83.84

34






74 125.126.127
124 26. (25 or 75) 74
75 21.26.124.125.126.127.

25 75
76



76
77 126.(25 or 75R).(134 or 84R)
127 27 77
78 21.79.132
129 28.(25 or 75R) 78
79 27.78.(134 or 84R).133 or 83 or 84R)
129.29
79
80



80
81



81
82 28.31
32 132 82
83 31.32.134.135
34 133 83
84 136
34 134.(133 or 83) 84






124 75.26 74

124
125 74.75.26
136
125
126 27.74.75.77.26
136
126
127 25.26.27.74.75 77

127
128



128
129 (28 or 78) (27 or 77) . 29 . (25 or 75R or 78) (79 or 78)

129
130



130
131



131
132 (27 or 82R or 77).28.31 .32.78.(25 or 75R or 82R) .(29 or 82)


132
133 (25 or 75 or 83 or 84). (27.73 or 83 or 84R). 34. 31 . 32. (26 or 74 . 84R or 83 or 84 . 78R) (28 or 83R or 78R)


133
134 (25 or 75 or 84). (27.77.79 or 84R) . 83 . (161.162 or 84) . (26 or 74.84R or 74R . 84)
136
134
135 83
136
135
136 84 125.126.134.135

136






161 (25 or 75 or 74) (134 or 84) [ (26 or 74) .(133 or 83 or 84)] *


161
162 (25 or 75 or 74) (134 or 84) [ (26 or 74) .(133 or 83 or 84)] *


162











Taita Route Locking








Route Locking



Released By Locked By After Controlling Relays restored released by
No Description Tcs Clear Delay after TC Occ'd Tcs Clear Delay with Tcs Occ'd No
74 Points & trap Down main & Loop 125T: 126BT: 126AT: 126T 60 Sec


74
75 Crossover Up & Down Mains 25T: 125T: 126BT: 126AT: 126T 60 sec


75
76 Spare





76
77 Crossover Up & Down mains 25T: 77T: 126T: 134BT: 134AT: (134T or 84R) 134BT 60 sec


77
78 Crossover Up Main & MU Storage 28T : 78T



78
79 Points & Trap Down Main & MU storage 78T: 134AT: (134T or 84R)



79
80 Spare





80
81 Spare





81
82 Points & trap Up Main & MU storage 82T: 28T: 28AT: (28T or 28AT) 60 sec


82
83 Crossover Up & down Mains 83T: 134T: 135AT: 135T: 82T: 31T 60 sec


83
84 Points & Trap Down Main & loop 134T



84
161 Permission lever Sidings Switchlock

A
B 161
162 Permission lever Sidings switchlock

A
B 162












A (25 or 75 or 74) (134 or 84) (26 or 74) (133 or 83 or 184)







B Released by 60 sec delay











Taita Control Table



No Description
Released By Track Circuits

Detects Points

Approach Locked by Track ccts Occupied Backlocked by Track ccts occupied Approach lock rel by delay when Tcs occ'd Appr & back lock rel by delay when Tcs occ'd Controls from signal ahead Remarks No



Clear No Occupied Normal Reverse N-R

21 Up Control Lever

21









21
23 Spare

23








(Up Outer Home 3rd road) 23
24 Spare

24








(Up Home 3rd road) 24
25 A Up Home NS to Up Main 25T 77T 25AT 28T 25 A
75 77

1174AT : 1224T : 1224AT 25T : (125T or 75N) 90 sec
D by 28A D/H
25 A
B
LS to Down Main
B
(161 : 162 w 74R) 75 74




25B controlled by push button B
26 Shunt from Down Main LS to Loop, Down Main or sidings
26
75 : (162w 74R . 161N)
74 : (161 w 74R) 125AT 125T 30 sec

Last wheel replacement 26
27 Shunt from Down Main LS to Down Main or Up Main
27


77 126AT : 126BT 126T
(126T or 126AT or 134BT ) 60 sec
Last wheel replacement 27
28 A Up Platform Starting NS to Up Main 28T 28AT 82T 31T 28 A
78

(1224AT or 25N or 75R) : (25T or 75R) : 25AT : 77T 28T
25AT 60 sec D by 31 D/H
28 A
B
LS to MU storage
B

78





28B controlled by push button B
29 Shunt from Down Main LS to MU storage
29
78 78
When operated 134AT : 78T 30 sec

Last wheel replacement 29
30 Spare

30

79






30
31 Up Main Starting NS to Up Main 82T 31T 31AT 1344T 31
82 83

(25AT or 28N or 78R) : 28T : 28AT 82T (28AT or 28T) 60 sec
D by 1344 D/H
31
32 Shunt and Up Starting from MU storage LS to Up Main 82T 31T 83T 31AT 1344T 32
83 82
When operated 82T 60 sec
D by 1344 D/H
32
33 Spare

33









33
34 Shunt and up starting from loop or siding LS to Up Main 134T 31T 83T 31AT 1344T 34

83 84
L134T 134T 60 sec
D by 1344 D/H
34
124 A Down Starting from loop or Siding

124 A



L134T : L134AT 125T 60 sec
Shows R only
124 A
B
MS to Down Main 125T 125AT 125BT 115T B
75 74




D by 115 D/H
B
125 Down Main Starting NS to Down Main 125T 125AT 125BT 115T 125
74 75

125BT : 126AT : 126T : (134BT or 126N)

D by 115 D/H
125
126 Down Platform Starting NS to Down Main 125T 125AT 126T 126AT 126BT 126
77

134BT : 134AT : (134T or 84R) : (135AT or 134N or 84R)

(126T or 126AT or 134BT) 60 sec D by 125 D/H
126
127 Shunt & Down Starting from Up Main LS to Down Main or Up Main 125T 125AT 126T 126AT 126BT 77T 25T 127

77
25AT 77T 30 sec
D by 125 D/H
127
128 Spare

128









128
129 Shunt from MU Storage LS to Down Main or Up Main
129

(79w 78N) 78??? When operated 78T (134AT or 79N)(28T or 78N) 30 sec

Last wheel replacement 129
130 Spare

130









130
131 Spare

131









131
132 Shunt from Up Main LS to Up main or MU storage
132
(78 w 82N)
88?? 31T: 31AT 82T : (28AT or 82R) 31T 60 sec

Last wheel replacement 132
133 Shunt from Up Main LS to Down Main, Loop, Sidings or Up Main
133
(79w 83R . 84N) (161w 83R . 84R . 162N)
83 (84w 83R) (162w 82R . 84R) When operated 83T : (134T or 83N) 60 sec

Last wheel replacement 133
134 A Down Home NS to Down Main MS to Loop LS to loop occupied 126T 126AT 134BT 134AT 134T 134 A
79 83 84

135AT : 135T : (1417AT or 135N) 134T 60 sec
D by 126 D/H
134 A
B

L134AT L134T 134T B
83 161 162 84




D by 124B D/H
B
C


C L134AT or L134T 83 161 162 84





134C controlled by push button C
135 A Down Outer Home NS to Down Main 134T 135T 135AT 135 A



1417AT : 1417T Rel by LS down 60 sec
D by 134A D/H May show “prepare to reduce to medium speed” 135 A
B


B







D by 134B D/H
B
136 Down Control Lever

136









136







Notes

These tables define the interlocking circa 1982 before the loop and other structures were removed.

I have several sources of information. Over the years there have been various changes including the removal of structures, metrication and probably other minor changes. Therefore this document must be seen as a guide to the Taita interlocking logic rather than as a 100% accurate definition.

I have the following questions about these tables (with some answers):

(a In the locking table under "Released by relays" there are four columns:

    Normal,  Reverse,  Normal - R Rec.,   Normal (N/R) Lock (The latter may be a latched relay).

The first two are self explanatory. What do the second two mean?

    Rec = Reciprocal?

(b) In the locking table I interpret "6T:6AT:39.40T" to mean  "6 track and 6A track and 39-40 track". Is this correct?

(c) In the locking table a dot rather than a colon is used as the delimiter e.g. 8.38. Is there a difference in meaning between the dot and the colon?

(d) What does D by D/H mean?

  • D Green relay
  • H Yellow relay

So D by 10 D/H means green if 10 signal green or yellow

(g) What does “Released by L.S. Down” mean?

This condition seems to apply when Route rather than Back locking is used.




Last Updated: Fri Aug 2013

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