Elevator rope order length: the four reeving formulas
RopeFactor estimates the required length of each hoist rope from travel, overhead, pit depth, machine location and roping ratio. Installation allowances are added to the calculated base length before the total is rounded up to the ordering increment.
Required dimensions
- Rise (travel) — distance from the lowest landing to the highest landing.
- Rope overhead (OH) — distance from top landing floor level to the centreline of the drive sheave. This is not the architectural overhead; see which dimension is used?
- Pit depth — distance from the lowest landing floor level to the pit floor. The rope runs into the pit at the bottom of travel, so it appears in every configuration.
Base length per hoist rope
The base rope length depends on machine location and roping ratio. The formulas below give the length of one hoist rope before installation allowances are added.
| Machine | Roping | Base length |
|---|---|---|
| Overhead | 1:1 | Rise + Pit + 2·OH |
| Overhead | 2:1 | 2·Rise + 2·Pit + 4·OH |
| Basement | 1:1 | 3·Rise + 2·Pit + 4·OH |
| Basement | 2:1 (underslung) | 4·Rise + 2·Pit + 6·OH |
On a basement 2:1 arrangement, overhead appears six times in the base-length formula. The overhead dimension should therefore be taken to the drive sheave centreline rather than using architectural overhead.
Allowances
Allowances cover hitch make-up, shortening during installation, and the second wrap on a double-wrap drive. They are added to the base length, and only then is the total rounded up to the stock increment — 10 ft, or 5 m.
| Allowance | Imperial | Metric | Applies to |
|---|---|---|---|
| Hoist extra | 25 ft | 7.6 m | every hoist rope |
| Double wrap | 20 ft | 6.1 m | every hoist rope, when the drive is double-wrapped — including at 1:1 |
| Governor | 20 ft | 6.1 m | the governor rope run |
| Compensation | 50 ft | 15.2 m | each compensation rope or chain |
The allowances above are planning values used for hitching, installation adjustment and double-wrap arrangements. They are not code requirements. Confirm final ordering allowances with the rope supplier and installation team before placing the rope order.
Governor and compensation runs
The governor rope forms a loop over the full rise, so both the rise and the pit appear twice:
- Governor = ROUNDUP( (2·Rise + 2·Pit + 2·OH + allowance) ÷ increment ) × increment
- Compensation, each = ROUNDUP( (Rise + allowance) ÷ increment ) × increment
Worked example
- Machine
- Overhead, 1:1, single wrap
- Rise
- 200 ft
- Overhead
- 8 ft
- Pit depth
- 8 ft
- Hoist ropes
- 6
Base = Rise + Pit + 2·OH = 200 + 8 + 16 = 224 ft
+ hoist extra 25 ft = 249 ft
ROUNDUP(249 ÷ 10) × 10 = 250 ft per rope
Governor = ROUNDUP((400 + 16 + 16 + 20) ÷ 10) × 10 = ROUNDUP(452 ÷ 10) × 10 = 460 ft
Order: 6 × 250 ft = 1,500 ft of hoist rope, plus 460 ft of governor rope.
The same job with the machine in the basement at 2:1 gives a base of 4·200 + 2·8 + 6·8 = 864 ft, which becomes 890 ft per rope after the allowance and rounding — 5,340 ft in total against 1,500 ft. The example shows the difference in rope quantity between an overhead 1:1 and a basement 2:1 arrangement.
See also
ISO 8100-2 minimum rope safety factor ASME A17.1 minimum rope safety factor by speed A worked calculation example — full ISO and ASME reports Elevator overhead: which dimension is used?