Door adjustment and maintenance

Priya's door overhauls follow the same order every time, and she made Tamsin write it on the inside cover of her field log: mechanical first, then the operator, then the protection, then the tests. "If you adjust the operator to suit a door that drags, you have hidden the problem until the next callback," she said. "Fix the door so it moves freely by hand, then make the operator move it properly, then prove the protection works, then measure." This lesson follows that order through a full door overhaul at Quayside car 4, and then looks at how door work fits into the maintenance control program and how door faults are recorded and trended.

Door work in the maintenance control program

Every elevator in service must have a written maintenance control program, required by Part 8 of the code, listing the maintenance tasks, how often they are done and how they are recorded. Doors take more of it than any other part of the elevator. Typical door tasks include examining and cleaning tracks, sills and gibs; checking hangers, rollers and up-thrust rollers; checking closers and relating cables; checking the clutch and its alignment with each landing's rollers; checking interlocks, contacts and restrictors; checking the reopening device; and checking closing force and timing. The intervals depend on how hard the doors work: a busy office car doing more than a thousand door cycles a day needs its doors examined far more often than a car in a small apartment building. The program must be available to the inspector and the owner, and the records must show what was done and found.

# Door cycles and roller wear: when will the hanger rollers need replacing? (illustrative)
cycles_per_day = {"Quayside car 4": 1400, "Larchmont": 420, "Tillicum car 1": 650, "Holloway car 1": 900}
roller_life = 2_500_000        # door cycles a hanger roller lasts in this service (maker's guide, illustrative)
cycles_done = {"Quayside car 4": 1_950_000, "Larchmont": 260_000, "Tillicum car 1": 2_300_000, "Holloway car 1": 800_000}
for car, per_day in cycles_per_day.items():
    left = roller_life - cycles_done[car]
    months = left / per_day / 30.4
    flag = "plan replacement now" if months < 6 else ""
    print(f"{car:<16} {per_day:5d} cycles a day, about {months:5.1f} months of roller life left {flag}")

Quayside car 4    1400 cycles a day, about  12.9 months of roller life left 
Larchmont          420 cycles a day, about 175.4 months of roller life left 
Tillicum car 1     650 cycles a day, about  10.1 months of roller life left 
Holloway car 1     900 cycles a day, about  62.1 months of roller life left

Quayside car 4 and Tillicum car 1 are both close to the end of their rollers' typical life, which is why car 4 was on the overhaul list. Door controllers on modern cars count cycles, and Northcrest copies the counts into its records at each visit so that wear parts are changed on a plan rather than after a failure.

Step 1: the mechanical door

With the car on inspection at the floor, the operator disconnected or the drive arm unhooked so the door can be moved by hand, and the hoistway protected, Priya began with the car door, then each hoistway door in turn. Each panel should move along its whole travel with an even, light push, without tight spots, noise or bounce. The checks are those of lesson 3: tracks clean and dry; hanger rollers free, round and quiet; up-thrust rollers at the maker's clearance; gibs complete, unworn and running freely in a clean sill; panels plumb and not rubbing the frame; relating cable tight and the panels arriving together; closers closing and locking the door from every position. On car 4, three hoistway doors had worn rollers with flat spots, one had a cracked gib and the floor 18 closer cable was frayed. All were replaced with the maker's listed parts.

Panel gaps are checked at the same time. The code limits the clearance between the panels and the frame and between panels when the doors are closed, so that a hand or object cannot be pushed through, with a small extra allowance for wear; panels that have sagged on worn hangers or been struck by carts often exceed it, and the fix is to reset the hangers or replace damaged panels. Sills are checked for damage and for the running clearance to the car sill.

Step 2: clutch, rollers and locks

Next comes the coupling between the car door and each hoistway door. The clutch vanes must pass each landing's interlock rollers with the right clearance when the car runs past, and grip them properly when the door opens. Too little clearance and the vanes strike the rollers in passing, which can open a lock in flight, as in lesson 4. Too much and the vanes miss the rollers or catch them late, so the hoistway door opens with a jerk or not at all. The clearance between the vanes and the rollers, and between the rollers and the car sill, is measured at every landing, and the maker gives the ranges. Interlocks are checked for engagement and contact sequence, car door contacts for operation, and the restrictor for its function outside the unlocking zone.

# Clutch vane to interlock roller clearance at each landing (maker's range, illustrative)
low, high = 6.0, 12.0
survey = {12: 9.0, 13: 8.5, 14: 4.5, 15: 9.5, 16: 13.5, 17: 8.0, 18: 9.0}
for floor, c in survey.items():
    if c < low:
        msg = "too close: vanes may strike rollers in passing"
    elif c > high:
        msg = "too far: vanes may miss or catch late"
    else:
        msg = "ok"
    print(f"floor {floor}: {c:5.1f} mm  {msg}")
bad = [f for f, c in survey.items() if not low <= c <= high]
print("adjust rollers at floors", bad)

floor 12:   9.0 mm  ok
floor 13:   8.5 mm  ok
floor 14:   4.5 mm  too close: vanes may strike rollers in passing
floor 15:   9.5 mm  ok
floor 16:  13.5 mm  too far: vanes may miss or catch late
floor 17:   8.0 mm  ok
floor 18:   9.0 mm  ok
adjust rollers at floors [14, 16]

Floor 14 was too close, the same landing where car 3 had nuisance reversals in lesson 2 and where the cars share a lobby wall that was rebuilt last year. Floor 16 was too far. Both rollers were reset on their slotted mountings and the survey repeated. Priya noted that a pattern of clearances drifting at several floors would point to the car itself, from worn guide shoes or a car running off centre, rather than to the landings.

Step 3: the operator

Only when the mechanical door moves freely and the coupling is right is the operator adjusted. On a closed-loop operator like car 4's, the work is mostly done with the door controller's service menu: run the learn cycle so the operator measures the door's travel and load, check that the open and closed limits are where the door stops, check the speed, acceleration and slow-zone parameters against the maker's settings and the data plate's minimum closing time, and check the obstruction detection and force limit. On an older resistor-and-cam operator like Tillicum's, the order is to set the cams for the slowdown points first, then the resistor bands for speed, then the checking and closing, and to time the door after each step.

Two points matter on every operator. Separate landing profiles, which some operators allow, must not be used to make one floor's door faster than the data plate allows to cover a drag problem. And after any change, the operator's settings must be written into the records, because the next mechanic needs to know what the door was set to when it was right.

Step 4: the protection and the tests

The reopening device is checked last before the tests: light curtain lenses cleaned, strips aligned and secured, the curtain's own status lights or self-test checked, and the reopening response tested at several heights, including low near the sill, at each landing. Nudging operation is checked if it is enabled. Then come the tests that prove the work: closing force at several landings, closing time through the code zone against the data plate, and a full set of door cycles at each landing on automatic. Priya's own final test, from lesson 1, follows: ride the car, block the doors by hand and with a cart, and watch the doors at each floor from the lobby side.

# Door overhaul record summary: anything left open?
items = {"tracks, sills, gibs": "done", "hanger and up-thrust rollers": "done (3 landings rollers replaced)",
         "closers and relating cable": "done (floor 18 closer cable replaced)",
         "clutch to roller clearances": "done (floors 14 and 16 reset)", "interlocks and contacts": "done",
         "restrictor": "done", "light curtain": "done", "operator learn and settings": "done",
         "closing force": "done", "closing time vs data plate": "pending"}
open_items = [k for k, v in items.items() if not v.startswith("done")]
for k, v in items.items():
    print(f"{k:<30} {v}")
print("car may return to service" if not open_items else f"NOT READY: {', '.join(open_items)}")

tracks, sills, gibs            done
hanger and up-thrust rollers   done (3 landings rollers replaced)
closers and relating cable     done (floor 18 closer cable replaced)
clutch to roller clearances    done (floors 14 and 16 reset)
interlocks and contacts        done
restrictor                     done
light curtain                  done
operator learn and settings    done
closing force                  done
closing time vs data plate     pending
NOT READY: closing time vs data plate

The record ends with a clear statement of whether the car can return to service. Tamsin's first overhaul record had the timing test still pending; Priya sent her back to time the door at every landing before signing it off.

Common door faults and their causes

Faults are trended as well as fixed. Northcrest's callback records note the car, the landing and the cause, and Lena reviews them monthly. A landing that appears three times in a quarter gets an overhaul whether or not its parts look worn, and a car whose door callbacks rise steadily gets its door maintenance interval shortened in the maintenance control program.