3:1 “Z” System
100% efficient pulleys
Instructions on how to perform a “T Analysis”
1) Draw out your system
2) Start by applying T=1 where you would haul/pull on the system
3) T value into a pulley is = T value out of pulley
4) T value behind the pulley is the sum of input & out put values
5) T values sum at intersections (i.e. pulley / prusik intersection of main line)
6) T value at load = mechanical advantage (MA) of system
Note / step 2
Note / step 3
HAUL: 3:1
T1
T1
Anchor
T2
T1
T1
Note / step 4
Note / step 6
T1
T2
T3 (T1 + T2)
Note / step 5
T3
load
3:1 “Z” System
100% efficient pulleys
T =1
= 50% Pulley
T=1
Anchor
T=2
T=1
= 100% Pulley
= 80% Pulley
T=2
T=1+2
= Prusik
T=3
load
80% efficient at moving pulley & 50% efficient pulley at COD/anchor
T=1
T = 0.8
Anchor
T = 1.2
T = 0.4
T = 1.8
T = 0.4 + 1.8
T = 2.2
load
50% efficient at moving pulley & 80% at COD/anchor
T =1
T = 0.5
Anchor
T = 0.9
T = 0.4
T = 1.5
T = 0.4 + 1.5
T = 1.9
load
Set of 4s with 5:1 MA & 4:1 MA
Fixed end of
8 mm cord
T1
T1
T2
Anchor
T1
T2
T2
T1
Load
T1
T4
(T2+T2)
T1
T2
T1
T1
HAUL, 4:1 MA
Fixed end of
8 mm cord
T1
T1
T1
T2
Anchor
T1
T1
T2
Load
T1
T1
T2
T1
T1
HAUL, 5:1 MA
T1
T5
(T2+T2+T1)
T2
T1
5:1 Compound “Z” System
HAUL = 5:1
= 100% Pulley
T1
= Prusik
T1
T2
T1
T1
T3 (T1 + T2)
Anchor
T2
T6
T3
T5 (T3 + T2)
load
11:1 Double Compound “Z” System
T1
HAUL = 11:1
T1
T1
T1
T2
T5 (T3 + T2)
Anchor
T10
T5
T1
T2
T3 (T1 + T2)
T3
T6
T11 (T5 + T6)
load