TLL Load Charts — Telescopic Boom, Swing Cab

Specialty: TLL (Telescopic — Swing Cab) · Domain: Load Charts (~35% of the exam) · ~22 min · OSHA 1926 Subpart CC + ASME B30.5-2025 (Authored & cited — pending SME review. Capacities reference the synthetic Academy Generic Telescopic — 90-Ton chart; no OEM chart is reproduced.)

1. The TLL chart — same telescopic grid, swing cab

Rated capacity = maximum allowable load at a given radius and configuration (ASME B30.5-2025 §5-1.1), read from a boom-length × loaded-radius grid printed for one setup (outriggers fully set, firm level ground, stated quadrant). Field: the chart, cap chart.

TLL = telescopic boom, swing cab — the operator cab is mounted on the rotating superstructure and swings with the boom (ASME B30.5-2025 §5-0.2.1, multiple/separate control stations for driving vs operating). Field: swing cab, all-terrain cab, upper cab.

The reading method is identical to any telescopic chart. The swing cab means the operator rotates with the load, so quadrant orientation is intuitive — but you still confirm the working area of operation against the chart, because over-side rates lower than over-rear.

Test trap: assuming a swing cab lets you ignore quadrant. The chart's area still governs — over-the-side is the weak direction regardless of where the cab faces.

Recap: TLL = telescopic grid + cab that swings with the boom; quadrant still comes from the chart.

2. Loaded radius, gross → net (same discipline)

Read the loaded radius — the radius with the load applied, always larger than the empty-hook radius from boom deflection and settle (§5-1.1). The cell is gross; net = gross minus every device, since blocks, balls, and slings count as load (§5-1.1.1(c)):

Test trap: 100 ft boom, 50 ft loaded radius = 20,500 gross (Academy chart). Block 1,000 + ball 400 + 30 ft jib erected but stowed → net well below 20,500. Read gross, forget the erected jib, and you overload.

Recap: loaded radius, then net = gross − all devices including any erected jib/aux sheave.

3. Luffing jib charts — the TLL-specific read

A luffing attachment is a boom/jib extension whose angle can be changed while working (ASME B30.5-2025 §5-0.2), unlike a fixed offset jib. Field: luffer, luffing jib. Its capacities live in a separate table indexed by boom angle and jib angle, bounded by a minimum and maximum jib angle for each configuration.

The minimum jib angle is a hard limit, not a suggestion.

Test trap: treating the "minimum jib angle" as a recommended starting point, or thinking the jib auto-retracts below it. Below the minimum, the jib can contact the main boom or pendants, or stability limits are exceeded — rated operation is not permitted below the minimum jib angle (manufacturer jib chart; §5-0.2).

Recap: luffing-jib capacity is read by boom angle + jib angle within the chart's min/max jib-angle bounds; below minimum = no rated lift.

4. Boom length, extend-under-load, outrigger position

• Use the actual boom length from the boom-length indicator (§5-1.9.1(e)) — not base length, not the maximum row.
• Extend/retract under load only within the chart's boom-motion maximum (§5-1.1.3(b)(10)); the permitted load in motion is typically lower than the static cell.
• Each outrigger position is its own chart; partial extension requires the matching chart at equal beam settings (§5-3.2.1.5(k)). On outriggers fully set = 85% stability basis; on rubber = a separate, lower chart (Table 5-1.1.1-1). Never interpolate across configurations.

Test trap: reading the maximum-boom-length row "for safety." A shorter actual boom at the same radius often rates differently — use the actual length.

Recap: actual boom length; extend under load per the note; one chart per outrigger position; no cross-config interpolation.

5. Reeving and two-block

Charted capacity assumes reeving can carry it: reeving capacity = single-line pull × parts of line; if the cell exceeds it, reeving governs (§5-1.7). An anti-two-block device must be operational before lifting (§5-1.9.10.1).

Recap: confirm parts-of-line capacity ≥ load; ATB working.

6. Worked go/no-go

Plan (Academy tele chart): 30,000 lb at 30 ft loaded radius, outriggers full, over-rear. Block 1,000 + slings 1,000 = 2,000 devices. No jib.

1. Total = 30,000 + 2,000 = 32,000 lb ≤ net?
2. 100 ft boom, 30 ft radius → 35,000 gross. Net = 33,000. 32,000 ≤ 33,000 → OK (thin margin).
3. If the boom deflects out toward 35 ft: 100 ft @ 35 ft → 31,000 gross, net 29,000 → NO LIFT. Re-check the loaded radius before committing.
4. Never exceed the cell (29 CFR 1926.1417(b)–(c)).

Recap: total with devices, verify at the loaded radius, keep the margin, never round up.

Common traps

• Assuming the swing cab removes quadrant concerns.
• Reading unloaded radius; treating gross as net; missing an erected jib.
• Operating a luffing jib below its minimum jib angle.
• Interpolating between outrigger or quadrant charts.
• Extending under load past the chart's motion note.

Quick check

1. Luffing jib below its charted minimum angle — permitted? → No (structural/stability limit; §5-0.2 + jib chart).
2. 100 ft boom, 40 ft loaded radius, gross 27,000; block 1,000 + ball 400. Net? → 25,600 lb.
3. Does a swing cab change which quadrant is weakest? → No — over-side is still weakest; read the chart's area.
4. Beams at mid-extension — which chart? → The matching partial-extension chart, equal settings (§5-3.2.1.5(k)).

Now test yourself

→ Practice: TLL — Load Charts — net-capacity, loaded-radius, luffing-jib angle limits, outrigger/quadrant selection, and extend-under-load reading on the Academy telescopic chart.