Author: Liz | Technical review date: 2026-09-28
What should you check before choosing a pendulum movement?
Check the pendulum assembly, mounting dimensions and required operation together. A movement that fits the dial may still be unsuitable for the proposed hanging components or the available swing space. Start with an exact model reference, a drawing of the pendulum and a representative housing, then ask the supplier to confirm the combination.
For HR1688P, Heng-Rong's August 12, 2026 supplementary knowledge base lists a pendulum load of 30 g, a length of 15 cm, several shaft options and an AA battery. It records stepping operation, not silent sweep. These are model-specific reference entries, not a guarantee that every pendulum described by similar numbers will work.
1. Identify the complete suspended assembly
Provide a drawing or photograph showing the pendulum rod, bob and connection to the movement. Identify any decorative additions and removable parts. Record the weight of the assembled parts that will be suspended, and explain which parts were included in the measurement.
Ask the supplier what its load figure includes. A bob-only weight and the weight of the complete suspended assembly describe different things. If the quoted specification does not define that boundary, obtain clarification rather than assuming the lighter measurement is the correct one to use.
Record pendulum length with clearly marked start and end points. Overall length, rod length and a distance measured from the suspension point are not interchangeable descriptions. The HR1688P knowledge-base entry gives 15 cm without defining those reference points, so a drawing is needed before using that figure as a production requirement.
2. Use the HR1688P reference as a starting point
The following table reproduces the relevant selection information from entry PT-15. Confirm the drawing and current supplied version before ordering. The record does not give a detailed test setup or establish whether the length and load figures apply simultaneously to every pendulum design.
| Selection item | Recorded HR1688P information | What to confirm |
|---|---|---|
| Pendulum load | 30 g | Which suspended parts are included |
| Pendulum length | 15 cm | Measurement start and end points |
| Listed shaft options | 8, 14.5, 17, 20, 23, 28 and 32 mm | Total shaft, usable thread and fitting positions |
| Battery | AA | Instructions for the exact supplied version |
| Operating type | Stepping | Whether this meets the intended sound requirement |
Do not use the pendulum load figure as a clock-hand torque rating. The source does not provide a corresponding hand-load limit in this entry. Send the intended hour and minute hands for a separate compatibility review, including their fittings and dimensions.
3. Match the shaft to the mounting arrangement
Measure the finished dial thickness at the mounting hole. Include the intended fixing components in the assembly review and ask for a drawing showing the usable threaded section. A shaft option labelled 20 mm does not mean that a 20 mm dial can automatically be mounted on it.
Check the space behind the dial for the movement body and its pendulum connection. Confirm access to the battery and setting controls after the housing is closed. For a replacement, photograph the old mounting arrangement from the front, side and rear; appearance from the front alone is not enough to select a compatible mechanism.
Keep the fixing method consistent with the supplier's instructions. If the assembly seems to require an improvised spacer, altered attachment or excessive force, pause and request clarification. Record any agreed changes in the drawing used for sample approval.
4. Allow room for the moving pendulum
Review the pendulum inside the intended case, including its distance from the back panel, side walls, glazing and decorative parts. Check clearance over the observed movement of the sample, rather than judging only its stationary position. A decorative feature that appears clear at rest may occupy space needed during motion.
The source does not specify a universal swing angle or clearance allowance for HR1688P. Do not invent one or borrow it from a different movement. Ask for the relevant installation guidance and validate the available space with the proposed pendulum and finished housing.
Keep the clock in the intended operating position during evaluation. Record the mounting method and any contact, interruption or instability you observe. Do not bend or modify the suspension connection to compensate for a mismatch unless the supplier has approved the change.
5. Separate stepping, pendulum motion and extra functions
The word pendulum describes a feature to check; it does not establish silent operation, a chime or a music function. The latest HR1688P entry explicitly says stepping. It provides no acoustic measurement, so this guide makes no decibel claim or promise that the movement will be inaudible in a quiet room.
If the project requires a particular sound characteristic, state it in the enquiry and evaluate a suitable sample in the intended setting. If a chime, melody or other additional function is required, obtain an exact model recommendation instead of assuming it is included with HR1688P.
6. Approve the complete sample configuration
Evaluate the movement with the intended pendulum, dial, hands and case. Follow the supplied fitting and battery instructions. Record the model, shaft version, pendulum drawing, assembled weight and housing revision so the result can be linked to a defined configuration.
Agree the observation period and acceptance criteria with the supplier. Check time display and pendulum operation as separate observations, and document any unresolved point before approving an order. A successful short sample observation does not establish service life or performance under conditions that were not evaluated.
If the bob, rod, hand set or housing changes after approval, review the affected checks again. Retain the approved sample and its records where practical. Confirm current quantities, packaging and delivery terms in the quotation rather than treating a technical reference table as a commercial offer.
Frequently asked questions
Is HR1688P a silent sweep movement?
The August 12, 2026 knowledge-base entry identifies it as stepping. If silent sweep is essential, ask for a separately confirmed option and do not relabel this model.
Can I reuse an existing pendulum?
Only after confirming its connection, complete suspended weight, length measurement and available swing space. Similar appearance does not establish compatibility.
Does the longest shaft option support the heaviest pendulum?
The source does not state such a relationship. Shaft selection concerns mounting dimensions; pendulum suitability requires its own configuration check.
Browse the pendulum clock movement range, then send your drawings and sample requirements through the Heng-Rong contact page. Identify HR1688P and the requested shaft version explicitly to support a model-specific response.