How to Inspect a 5 Ton Chain Hoist Dry Brake: CB050 Manual

Inspect a 5 ton chain hoist dry brake by checking the friction surfaces for oil or grease, checking the brake pawl, pawl pin and pawl spring for deformation or significant wear, and reading the friction plate for even thickness before the unit goes back into service. The condition that decides most of these calls: on the Harrington CB050, a contaminated or worn dry brake is replaced, not cleaned and relubricated.

Everything below is tied to the Harrington CB050 and the owner's manual written for it. A different 5 ton hoist can use a different brake arrangement, different figures and different discard values, so treat this as a model-specific walkthrough rather than a five-ton procedure that travels. The parts named here, the figures the manual points to, and its discard table all belong to that document.

Start With the Dry Brake, Not the Oil

If a CB050 is lowering loads a beat late and the brake area looks wet, the move that pays is pulling the unit out of rotation and planning on brake parts, not wiping the faces down and running it while the next failure builds. That choice costs a hoist out of service for a shift and a set of parts, which is real money in a busy bay. The other choice costs a load that does not stop where the operator expected it to, and on a 5 ton unit working over an aisle or a picker, those two costs do not trade well against each other. This is the one place in the inspection where I would spend the downtime without much argument.

The reason sits in what the brake is doing. The CB050 runs dry friction discs, and the manual states plainly that oil does not go on friction surfaces, because a dry brake holds by surface contact between disc and plate rather than by a film of anything. Whatever ends up between those faces, whether oil, grease or a smear of chain lubricant picked up during handling, sits in the gap the brake depends on, which means the same load that stopped cleanly last week now creeps. Improper braking may cause improper load lowering, so a slow-lowering complaint is an inspection trigger, not a lubrication trigger. Picture a receiving bay where a CB050 drifts a few inches after the operator lets go of the pendant and the plate carries an oil sheen with a dark ring where the disc sits; that is a hypothetical, not a recorded case, and it ends with parts on order.

Inspect Pawl, Pin, and Spring First

Start on the engagement side, before the friction faces get any attention. The brake pawl, the pawl pin and the pawl spring should not be deformed, scarred or showing significant wear, and the manual's answer to any of those conditions is replacement of the part rather than adjustment. Brake surface damage from scratching or gouging by foreign matter belongs in the same visual pass, because grit or a burr that scored the face has already changed the geometry the disc has to sit against.

The order is not arbitrary. The pawl and spring are what engage and release the brake; the friction disc is what does the stopping once they have engaged. If the pawl is deformed or the spring has lost its push, the friction faces can look perfect and the brake still misbehaves, which means a verdict taken from the friction plate alone is not a verdict on the brake. A pass at this step is easy to state: all three parts straight, unscarred and unworn, and no fresh scratches or gouges on the brake surfaces. Anything else is a parts order, and the friction parts get judged after the engagement parts are sound.

Look for Oil, Grease, Scars, and Gouges

On the friction plate, the surface should be free of grease, oil, scars, gouges and wear. On the friction disc, the surface should be free of scars, gouges and wear, and damage there is called out for replacement. Those two lines look almost the same and are not: the plate carries the contamination wording, the disc carries the surface-damage wording, and both are judged before anything is measured.

The manual sets the bar at free of, not lightly contaminated, which means there is no acceptable film to argue about and no useful distinction between a sheen and a puddle on a face that is supposed to run dry. A plate that looks clean but carries a gouge fails the same visual check, because the disc needs flat contact across its whole face and a gouge removes that contact from a patch of it. If a face looks wet again shortly after being wiped, the source is upstream of the brake, likely a lubricated chain, a fitting, or a greasy glove during the last reassembly, and that source is what has to be dealt with before a new plate goes in behind it.

Measure Even Thickness Across the Plate

The friction plate gets both a visual and a measurement, and the manual asks for uniform thickness with an outer thickness that is not thinner than the inner thickness. That comparison is the whole measurement instruction: readings taken at the inner band and the outer band of the plate, held against each other, not a single number jotted down and filed.

A plate wears against a disc that touches it across its face, so a plate that is thinner at the rim than at the bore has either worn unevenly or distorted, and either way the contact patch during braking is not the full face the design assumes. Which means a plate can come out of the visual check clean and still fail on profile, and a plate that fails on profile is not a candidate for a second look later. This step is also where the pass gets recorded rather than remembered: inner and outer readings written down with the date, so the next inspection has something to compare against instead of an opinion.

Decide Replace or Return to Service

There are two endings to this inspection. The first is a pass: no oil or grease on the friction surfaces, no scars or gouges on plate or disc, no significant wear on the friction parts, thickness that is even from inner to outer and at or above the manual's discard value, and a pawl, pin and spring that are straight, unscarred and unworn. The second is a parts order covering whatever failed, with the failed parts replaced rather than worked around. There is no third ending where the brake goes back together with oil on the friction faces and a note to watch it.

That hard line comes from what the brake controls. It governs how a load comes down, so any uncertainty about friction is uncertainty about load control, and a monitor-it default simply moves the decision to whoever happens to be standing under the next lift. The manual also links improper braking to improper load lowering, which is the practical version of the same point: the failure mode is not a noisy brake, it is a load that does not go where it was sent.

Do Not Quote a Discard Thickness Without the Table

The manual sends you to Table 5-9 for the discard value that the plate thickness is measured against, and this walkthrough deliberately prints no number for it. The threshold belongs to a specific model and manual revision, so a generic five-ton figure copied from somewhere else would be a confident wrong answer, and a copy of that table that has lost its column headings or its unit is worse than no number at all.

The procurement side is where this gets closed out. Confirm the model and the unit's data plate match the manual in hand, get the manual revision that covers that unit, write the Table 5-9 value and its unit onto the work order so the measurement has a reference sitting next to it, and make sure nobody substitutes a figure borrowed from another 5 ton hoist in the fleet. Two hoists of the same capacity are not the same brake.

The delayed stop from that receiving bay ends one of two ways. One is a brake signed off with clean, unworn, evenly thick friction parts and sound engagement parts, backed by a measurement compared against a value someone actually looked up for this model. The other is a parts order and a hoist that sits until the new brake goes in. Either way, the sign-off rests on a number that came from this unit's own manual, not on how the brake felt on the last lift.