Maintenance of Deck Machinery — Intervals, Greasing and Overhauls

1. Why the routine is different from engine room machinery

Deck machinery requires periodic inspection and maintenance in order to get efficient operation. The harsh climatic conditions to which it is subjected in its exposed location, as compared to engine-room machinery, make it very important to follow regular maintenance schedules, in order to avoid costly failure.

Two consequences follow:

• Totally enclosed equipment with oil bath lubrication for gears and bearings is standard (Chapter 1), so the maintenance is concentrated at the points that cannot be enclosed — the open final gears, the grease points, the seals and the electrical enclosures.
• The machinery may not run for weeks and then be required at full load, so a defect that would show up in a running machine stays hidden until the worst possible moment. The schedule is the only thing that finds it.

2. The general items

The general items on the schedule are:

• Grease all points on winches, blocks, cranes, hooks, shackles and so on — weekly.
• Every three months, carry out an inspection of ancillary equipment such as chains, rings, hooks, swivels and blocks.
• Regular overhaul to be done as per the PMS schedule or every 6 months, whichever is shorter.
• SWL and identifying marks to be always visible.
• The file containing the certificates should be examined, to ensure that all are valid.

The last two are not maintenance in the ordinary sense, but they are the items that stop a ship working cargo. An unmarked or uncertificated shackle takes the whole lifting appliance out of service, and the marks are what the surveyor looks for first.

3. Winches

Winches should be overhauled, especially the brakes, as per the PMS schedule or every 6 months, whichever is shorter.

The brake is called out separately because it is the item that decides whether the winch is safe rather than merely working. A winch whose motor and gearing are perfect but whose brake will not hold is not a winch; it is a hazard. On a mooring winch the barrel brake may be designed to withstand the breaking strength of the mooring wire (Chapter 5), and a brake in that duty is doing real work every time the ship moves on its lines.

4. Cranes and lifting equipment

Cranes and other lifting equipment are to be de-rusted, overhauled and painted as per the PMS schedule or every 12 months, whichever is shorter.

The interval is longer than the winch interval because the crane's brakes are spring applied and fail safe, and because the crane is not worked continuously on a wire under permanent strain. It is still an annual job, and it includes the structure as well as the machinery — which is why it is de-rusting and painting as much as it is overhauling.

5. Hydraulic systems

The most important thing about any hydraulic system is to ensure that the hydraulic oil remains clean, and that is done by regular inspection of filters. The reasons the oil must be kept clean — oxidation, water, metal wear and the jamming of valves with fine clearance — are in Chapter 3.

Three further items belong to the routine:

• Any protective boots fitted over rams should be periodically examined. A split boot lets grit onto the rod, and the rod carries it into the cylinder.
• Flexible hoses should be periodically examined.
• Hydraulic hoses should have their date of manufacture printed on them, and can be expected to have a life of about five years.

The hose date is the one item on a deck hydraulic system that gives an unambiguous age without any measurement, which is exactly why it is printed on the hose.

6. The windlass

The windlass sits in the most exposed position of any machine on the ship, and it is built so that its maintenance demands are an absolute minimum by design: the gearing is arranged so that little routine attention is needed, and what is needed is confined to a small number of grease points. The construction that makes this possible, and the points that still have to be greased, are in Chapter 4 section 7.

For the schedule it falls into the same bracket as the winches — the six-monthly overhaul in section 3, with the cable lifter brake under the brake rules in section 8 — and it takes the weekly greasing in section 2 like everything else on deck.

7. Hatch covers

The hatch cover routine, the seal work and the survey intervals are in Chapter 8 section 6, section 7 and section 8. In the schedule the covers appear at three points: each port, annually with the hull survey, and at the five-yearly special survey which requires a hose test.

8. Brakes, generally

Brakes are the common thread running through this volume — the cable lifter brake in Chapter 4, the barrel brake in Chapter 5, the disc and band brakes on the crane in Chapter 7, and the main and centrifugal brakes on the davit winch in Chapter 9. Three rules apply to all of them:

1. They are overhauled on the shorter of the PMS interval or the maker's figure — six months for winches and the windlass, twelve months for cranes.
2. A brake that has been replaced or adjusted must be tested before the machine is returned to service. The davit brake test in Chapter 9 — hold the load, then arrest it after a limited free run — is the model.
3. A brake that has been adjusted to stop slipping is not thereby proved to be working. Over-adjustment is the commonest way to make a brake appear to pass while removing the margin that made it safe.

9. The intervals at a glance

The schedule is a floor, not a ceiling. Anything found at any of these inspections which affects safety takes the machine out of service until it is put right — and on a windlass, a crane or a davit, that decision is not the engineer's alone to defer.