At a Glance: 5 Key Things to Know About Mora Clock Parts
- 1. The Movement is the Heart — Authentic Mora clocks use either a 30-hour or 8-day weight-driven movement; understanding which you have determines your winding routine and replacement options.
- 2. Weights Drive Everything — The hanging weights are the power source; if a weight is missing or damaged, the clock will not run. Replacements are available and straightforward to fit.
- 3. The Pendulum Controls Accuracy — A bent, damaged, or incorrect pendulum rod or bob will cause erratic timekeeping; this is one of the most common and easiest parts to replace.
- 4. The Winding Key Must Match — 8-day movements require a specific key size (typically 4mm, 5mm, or 6mm); using the wrong size can damage the winding arbor.
- 5. Modern Replacement Movements Exist — When an original movement is beyond economic repair, a quality modern longcase movement can be fitted — preserving the clock's beauty while restoring reliable function.
The weight-driven movement at the heart of an authentic antique Mora clock — a masterpiece of pre-industrial engineering.
Introduction
Every antique Mora clock is a collection of carefully made, interdependent parts — and understanding what each one does is the first step to keeping your clock running well and knowing when something needs attention. Whether you have just purchased your first Mora clock or have owned one for years, this guide will walk you through the key Mora clock parts, explain their function, and help you decide when repair or replacement is the right course of action.
At Mora Clock, we stock a range of parts and accessories for antique longcase movements, including winding keys and replacement movements. Everything we sell is selected to be compatible with the types of movements typically found in genuine Swedish Mora clocks.
The Movement: 30-Hour vs 8-Day
The movement is the mechanical engine of the clock — the assembly of gears, springs, levers, and escapements that converts the energy of the falling weights into the regulated beat of the pendulum and the turning of the hands.
The movement sits within the hood of the clock, visible through the glazed door on many examples.
Antique Mora clocks were fitted with one of two movement types:
The 30-hour movement is the simpler and earlier of the two. It is driven by a single weight, wound by pulling a chain or rope, and must be wound every day. These movements are robust and relatively straightforward to service, but their daily winding requirement makes them less convenient for modern owners.
The 8-day movement became increasingly common from the late 18th century onwards and is the type most frequently encountered today. It has two weights — one powering the going train (timekeeping) and one powering the strike train (the bell or gong) — and is wound with a key once a week. The 8-day movement is generally considered more refined and is the type most collectors prefer.
When assessing a movement for condition, look for: even wear across the gear teeth, pivot holes that are not elongated or worn oval, and a clean, dry escapement. A movement that has been run without oil for many years will show accelerated wear and may require professional bushing before it can be reliably used again.
The Weights
The weights are the power source of the clock. In a 30-hour movement, there is typically one weight; in an 8-day movement, there are two — and they are not interchangeable, as the going and strike trains often require different weights to run correctly.
The weights hang within the trunk of the clock, visible through the glazed or panelled door.
Original Mora clock weights are typically cast iron or lead, enclosed in a cylindrical iron or brass shell. If a weight is missing, cracked, or has lost its shell, replacement weights are available from horological suppliers. It is important to match the weight of the replacement as closely as possible to the original, as the movement is calibrated to run with a specific load.
Weights should be inspected periodically for corrosion, particularly on the hooks and lines by which they hang. A corroded or weakened line is a safety risk as well as a mechanical one — replace it before it fails.
The Pendulum
The pendulum regulates the speed of the movement. Its length determines the rate at which it swings, and therefore how fast or slow the clock runs. A standard longcase pendulum beats once per second — known as a seconds pendulum — and is approximately 99 cm long from the suspension point to the centre of the bob.
The pendulum hangs the full height of the trunk — its length is precisely calibrated to the movement.
The pendulum consists of three main parts: the suspension spring (a thin strip of spring steel that allows the pendulum to swing from the movement), the pendulum rod (typically a flat steel or wooden rod), and the pendulum bob (the disc at the bottom, which can be raised or lowered to regulate timekeeping).
Common pendulum problems include: a bent or kinked rod (which causes erratic swing), a cracked or missing suspension spring (which prevents the pendulum from hanging correctly), and a seized rating nut (which prevents bob adjustment). All of these parts can be replaced individually without replacing the entire pendulum assembly.
The Dial and Hands
The dial is the face of the clock — on a genuine antique Mora clock, this will be hand-painted on a tin or paper ground, with Roman numerals and often a maker's inscription. The hands are hand-cut from steel or brass.
An original hand-painted dial — irreplaceable and deserving of careful preservation.
Dial and hand problems are usually cosmetic rather than mechanical. Foxing, yellowing, and minor flaking on an original dial are signs of age and should be left alone — they are part of the clock's character and history. If the dial is severely damaged or illegible, a specialist paper conservator can sometimes stabilise and clean it without replacement.
Hands that are bent can often be carefully straightened by a clockmaker. Missing hands can be replaced with period-appropriate reproductions, though finding an exact match for an 18th-century original may require a specialist supplier.
The Strike Mechanism: Bells and Gongs
Most 8-day Mora clocks include a strike mechanism that sounds the hours on a bell or coiled gong. The bell is mounted within the hood and struck by a hammer driven by the strike train. Common strike problems include: a hammer that fails to lift (worn cam or worn hammer tail), a bell that sounds dull (loose mounting or cracked bell), or a strike that does not correspond to the correct hour (the count wheel or rack has slipped).
Bell replacements are available in a range of sizes and tones. If your clock has a coiled gong rather than a bell, these are also readily replaceable and can significantly improve the sound quality of an older movement.
When Does a Modern Replacement Movement Make Sense?
This is the question we are asked most often by owners of antique Mora clocks whose original movement has failed beyond economic repair. The answer depends on your priorities.
A clock with a replaced movement can still be a beautiful and functional piece — the key is choosing the right replacement.
If the clock has significant collector or monetary value, preserving the original movement — even in non-running condition — is usually the right choice. A non-running original movement can often be restored by a skilled clockmaker, and replacing it with a modern movement will reduce the clock's value to a knowledgeable buyer.
If the clock is primarily a decorative and functional piece — and the original movement is beyond repair — a quality modern longcase movement is a practical solution. We stock the Longcase Clock Mechanism Set, which is compatible with the case dimensions of most antique Mora clocks and provides reliable 8-day timekeeping with a traditional pendulum and weights. It is a sympathetic solution that keeps the clock alive and ticking without compromising the beauty of the case.
Browse our full range of Mora clock parts and accessories — including winding keys in 4mm, 5mm, and 6mm sizes — or get in touch if you need advice on the right parts for your specific clock.
Mora Clock — specialists in authentic antique Swedish Mora clocks and the parts to keep them running.