Sessions Clock Click Failures and Safe Winding

Sessions mantel clocks with loose click rivets that slip during winding create dangerous situations where mainspring power releases suddenly striking the owner's thumb with painful force. When rapid winding or worn click mechanisms allow the pawl to slip upward engaging only partially with ratchet teeth, the click eventually fails completely releasing wound mainspring tension through the winding key directly into the clockmaker's hand. This common problem with Sessions movements stems from thin ratchet wheels and clicks secured by straight rivets that loosen over time, combined with poor winding technique where owners release key pressure before verifying click engagement. This guide covers complete understanding and prevention of click failures during winding. You'll learn proper winding technique ensuring click engagement before releasing key pressure, recognizing worn click components requiring replacement before failure occurs, upgrading Sessions clicks using shoulder rivets and steel springs for permanent reliability, emergency let-down procedures when clicks fail mid-winding without injuring yourself or damaging the clock, and understanding why Sessions movements are particularly prone to click failures requiring special attention. The key to preventing painful click failures is never trusting Sessions clicks without inspection, always winding slowly enough to hear each click engagement, and installing shoulder rivet upgrades replacing the original straight rivet design that inevitably loosens.

Understanding Click Function and Failure

How Clicks Prevent Mainspring Release

The click is a spring-loaded pawl that engages ratchet wheel teeth. When you wind a clock, the ratchet wheel rotates forward. The click rides up each tooth then drops into the space behind it. This ratcheting action allows forward rotation during winding while preventing backward rotation when you release the key. Without the click, mainspring power would immediately unwind when you let go.

The click spring provides tension holding the pawl against the ratchet wheel. Proper tension ensures the click drops decisively into tooth spaces. Too much tension creates excessive friction during winding. Too little tension allows the click to bounce or fail to engage properly. The balance is critical for reliable operation.

During winding, mainspring power constantly tries to rotate the winding arbor backward. The click is the only component preventing this reverse rotation. Every time you wind a clock, you're loading more power into the spring. This increases the force trying to escape backward. A worn or improperly adjusted click that seemed adequate with light winding may fail when the spring reaches higher tension.

Why Sessions Clicks Fail

Sessions used thin ratchet wheels and clicks compared to other manufacturers. The thin design reduces material cost but creates alignment problems. When the click rivet loosens even slightly, the click can shift upward away from the ratchet wheel. This misalignment prevents full tooth engagement. The click tip catches only the upper portion of teeth rather than dropping fully into tooth spaces.

Partial engagement rapidly damages the click tip. The concentrated force on the small contact area deforms the metal. Once the tip becomes rounded or worn, it slips over teeth even when properly aligned. The wear progresses quickly. A click that engages reasonably well today may fail completely within a few windings.

Sessions originally used straight rivets to mount clicks. Straight rivets are difficult to tighten properly. Too loose and the click shifts causing misalignment. Too tight and the click binds preventing free movement. By the time owners notice clicking sounds are wrong, the rivet and click holes are worn to sloppy fit. Simply retightening worn straight rivets rarely provides lasting repair.

The Danger of Click Failure

When a click fails during winding, mainspring power releases through the winding key directly into your hand. The force is substantial - enough to spin the key violently and potentially break fingers or thumbs. The surprise element compounds the danger. You're concentrating on winding when sudden impact occurs. Instinctive reaction is often wrong - jerking your hand away can cause additional injury.

Click failure can also damage the clock. If you're holding the key firmly when the click lets go, the sudden rotation may twist or break the winding arbor. The mainspring itself can suffer damage from uncontrolled release. Components throughout the movement experience shock forces they weren't designed to handle. What started as a worn click becomes expensive comprehensive repair.

Experienced clockmakers develop healthy respect for this danger. They know owners who've suffered broken bones from click failures. They've repaired movements damaged by uncontrolled mainspring release. This isn't theoretical - it's real hazard requiring preventive measures and safe practices.

Proper Winding Technique

Slow Steady Winding

Wind clocks slowly with steady controlled motion. Rapid winding doesn't allow you to monitor click engagement properly. You should hear each click distinctly. If you're winding so fast that clicks blur together, you're going too fast. Each turn of the key should be deliberate. You maintain control throughout the winding process.

Fast winding increases click bounce likelihood. The rapid acceleration as each tooth releases creates momentum. The click can bounce over the next tooth space rather than dropping in. This bounce puts extra stress on click components. It also creates the conditions where a worn click will fail. Slow winding eliminates these dynamic forces.

Listen to the clicking sound. Healthy clicks produce sharp distinct sounds as the pawl drops into tooth spaces. Changes in sound indicate problems. Weak clicking suggests worn click tip or insufficient spring tension. Irregular clicking indicates damaged ratchet teeth or click misalignment. Any sound change should trigger immediate inspection before continuing to wind.

Verify Click Holds Before Releasing

The most critical safety practice is verifying the click holds before releasing key pressure. After each turn, pause briefly with tension on the key. Listen for the click engagement. Feel through the key whether the click is holding. Only after confirming engagement should you release pressure to reposition your hand for the next turn.

This verification adds just seconds to winding time but dramatically improves safety. You confirm the click is working before releasing control. If the click fails to hold, you still have the key firmly gripped. You can implement emergency let-down procedures instead of experiencing sudden violent key rotation.

Many clockmakers ease the click into gear rather than releasing suddenly. Turn the key forward until you feel the next tooth engage. Apply slight backward pressure feeling the click catch. Once you confirm the catch, release forward pressure and reposition for the next turn. This technique provides maximum control and click verification.

Using Let-Down Keys for Unfamiliar Clocks

When winding clocks you don't know well, use a let-down key instead of standard winding keys. Let-down keys have slotted shafts that slip over winding squares. The slot allows controlled let-down if the click fails. The key won't spin violently because it's not solidly attached to the winding square.

Let-down keys come in narrow and wide slot sizes matching different winding square dimensions. The wooden handle provides comfortable grip. While primarily designed as mainspring let-down tools, they provide excellent safety for winding unknown clocks. If the click fails, you can let go with one hand to retrieve the let-down tool from your pocket without losing complete control.

Some clockmakers keep let-down keys in their pockets when servicing multiple clocks. The small investment in these tools prevents injuries. They're available from clock supply houses. Having proper tools demonstrates professional approach to clock work. It also shows respect for the real dangers involved in the craft.

Inspecting and Replacing Clicks

Visual Inspection Criteria

Remove the movement from the case for proper click inspection. You need clear view of ratchet wheels and clicks. Check rivet tightness by trying to move the click laterally. Any play indicates the rivet has loosened. Even slight looseness allows click misalignment causing eventual failure.

Examine the click tip closely. A healthy tip has sharp defined edges that drop cleanly into ratchet teeth. Rounded or worn tips indicate the click has been operating with misalignment or insufficient spring tension. Once tips wear, they won't engage reliably regardless of other corrections. Worn tips require click replacement.

Check the ratchet wheel teeth for damage. Worn teeth show rounding on leading edges. Damaged teeth may have chips or burrs. The click should drop smoothly into tooth spaces without binding or catching. Rough operation indicates either click or ratchet wheel problems requiring correction.

Testing Click Spring Tension

Click springs must provide adequate tension without binding. Press the click away from the ratchet wheel using a screwdriver blade. The spring should return the click decisively when you release pressure. Weak return indicates worn or damaged spring requiring replacement.

Observe how the click engages ratchet teeth. The pawl should drop into tooth spaces with audible snap. If the click settles slowly or silently, spring tension is inadequate. Insufficient tension allows the click to bounce or slip during operation. Replace weak springs before failure occurs.

Compare spring tension between time and strike trains if the movement has both. They should feel similar. Significant differences suggest one spring is weaker than the other. The weaker spring needs replacement even if it's currently functioning. It will fail sooner than the stronger spring creating service issues.

Shoulder Rivet Upgrade

Replace original straight rivets with shoulder rivets for permanent repair. Shoulder rivets have enlarged heads and precision-diameter shoulders. The shoulder provides exact fit in the click hole. The large head distributes clamping force preventing rivet loosening. The rivet can be tightened securely without binding click movement.

Commercial shoulder rivets from clock suppliers often don't fit Sessions applications well. Many clockmakers make custom shoulder rivets from steel rod. Turn the shoulder diameter to match click hole size. The fit should be close without being tight. Turn the head diameter larger than the click width. Cut to proper length and rivet securely.

Steel rivets are preferable to brass for this application. Steel provides better strength and wear resistance. The rivet experiences considerable force during operation. Brass is too soft for reliable long-term service. Steel rivets won't loosen and wear like original brass rivets do.

Emergency Let-Down Procedures

When Click Fails During Winding

If you realize the click isn't holding during winding, don't panic. Maintain firm grip on the key. Don't release suddenly hoping the problem will resolve itself. You have mainspring power loaded and no click holding it. The key is the only thing preventing uncontrolled release. Keep control while you assess options.

The safest immediate response for preventing personal injury is yanking the key quickly from the clock. This removes the key from the danger zone. However, this action usually damages the clock. The mainspring releases through whatever components it can drive. Gears may strip, pivots may break, or the mainspring itself may suffer damage. This is last-resort action when protecting yourself takes priority.

If the clock is heavy, mounted to a wall, or someone can hold it steady, you can attempt controlled let-down. Use both hands on the key. Turn backward very slowly - perhaps a half-turn at a time. Listen and feel for any catching or binding. This procedure risks injury to both hands but may save the clock from damage. Only attempt this if you have help and experience.

Mantel Clock Let-Down Method

For mantel clocks that can be moved easily, lay the clock on its back on a soft surface. The weight of the mainspring plus movement creates friction helping control release. Slowly rotate the entire clock case. This unwinds the mainspring gradually. The case weight and friction provide resistance that the bare winding arbor doesn't have.

This method works best with clocks having substantial case mass. Light clocks provide insufficient resistance. Very powerful mainsprings may overpower case friction. The technique requires large clear space for rotating the case. It's not practical for tall or oddly-shaped cases. However, when applicable, this is safer than other emergency methods.

Keep your hands away from the winding key during case rotation. Let the key rotate with the case. Don't try to control it. Your hands should grip the case sides only. Once the mainspring fully unwinds, remove the key and address the click problem before attempting to wind again.

Wall Clock Let-Down Method

Wall clocks present more challenges than mantel clocks. The case can't be rotated easily. The mounting restricts access. If possible, remove the clock from the wall while maintaining key control. This requires help. One person holds the key while another unfastens mounting hardware. Once off the wall, treat it like a mantel clock.

If the clock can't be removed easily, you must attempt controlled backward turning of the key. Use both hands if possible. Turn very slowly with constant control. Each half-turn reduces mainspring tension slightly. The process is slow and nerve-wracking but may succeed without damage. Don't rush - rushing increases accident risk.

Have someone available to call for help if things go wrong. Serious hand injuries from click failures require immediate medical attention. Don't attempt heroic saves of clocks at the expense of your hands. Clocks can be repaired or replaced. Hands can't. Maintain perspective about relative values.

Upgrading Click Systems

Dual Click Installation

Some clockmakers install two clicks on each ratchet wheel for redundancy. If one click fails, the second prevents mainspring release. This is perhaps overly cautious for most applications but provides peace of mind. The installation requires adequate space on the ratchet wheel for two pawls.

Position the dual clicks opposite each other on the ratchet wheel. This balanced arrangement distributes forces evenly. Both clicks should engage simultaneously during winding. If only one clicks, the other isn't properly adjusted. Adjust positions until both engage cleanly.

Use shoulder rivets and steel springs for both clicks. The redundancy is worthless if both clicks use the same weak original design. Quality components in dual installation provide extremely reliable system. While one clockmaker's experience had a spring fail, the backup click prevented any problems. This demonstrates the value of redundancy.

Steel Click Spring Wire

Replace original brass click springs with steel spring wire. Steel provides better strength and fatigue resistance than brass. The springs experience constant flexing during operation. Brass fatigues more quickly than steel leading to eventual failure. Steel springs outlast brass springs by large margins.

Form steel springs from music wire or spring steel wire available from hardware suppliers. The wire diameter should match or slightly exceed original spring dimensions. Bend to proper shape using round-nose pliers or appropriate forming tools. The bends should be smooth without sharp transitions that concentrate stress.

Temper the springs after forming if you've used untempered wire. Heat to cherry red then quench in oil. This treatment provides spring characteristics. Alternatively, purchase pre-tempered spring wire and form cold. The wire will work-harden slightly during bending. Test the finished spring strength against working original springs from other movements.

Ratchet Wheel Alignment Disk

Later Sessions movements included steel disks mounted over ratchet wheels. These disks help maintain click alignment even when rivets loosen slightly. The disk prevents the click from shifting upward away from the ratchet wheel. This simple addition dramatically improves reliability.

For earlier Sessions movements without disks, consider adding them during service. Fabricate disks from thin steel sheet. The disk should be slightly larger than the ratchet wheel diameter. Drill a center hole matching the winding arbor. Mount the disk with spacers positioning it just above the ratchet wheel surface.

The disk must not interfere with click operation. It should clear the click as it engages teeth. The clearance needs to be close - just enough to prevent binding. Proper spacing requires trial and error. Test thoroughly before final assembly. The disk adds complexity but provides significant reliability improvement for problem movements.

Special Considerations for Different Clock Types

Cuckoo Clock Chain Winding

Cuckoo clocks use chains rather than keys for winding. Pull chains smoothly in continuous motion. Hand-over-hand technique works well for clocks with long chain runs. Don't pull too fast - steady moderate speed is appropriate. Fast pulling doesn't hurt anything but isn't necessary.

Stop pulling about eight to ten inches before weights reach the case. Let the weights stop their rotation from chain twist. This prevents shock when weights contact the case. You can then pull them up the remaining distance slowly until they gently contact the clock. This technique reduces wear on chain wheels.

When releasing chain pressure, do so gradually. Don't just drop the chain. The sudden release can cause chain wheel bounce. While cuckoo clicks are generally more reliable than mantel clock clicks, they still deserve respect. Verify you hear the click holding before fully releasing the chain.

Weight-Driven Movements

Weight-driven movements use pulley systems rather than direct winding. The clicks still perform the same function preventing weights from falling when you stop cranking. Test clicks on weight-driven movements using the same criteria as spring-driven movements. Worn clicks are just as dangerous regardless of power source.

The lower forces in weight-driven systems mean clicks last longer before showing problems. However, gravity is constant force. Once a weight starts falling from click failure, it won't stop until something breaks or the weight reaches the floor. The sustained force can cause different damage than sudden mainspring release but is equally serious.

Check weight cord attachment points during click inspection. Worn cords can break during winding creating sudden release similar to click failure. The weight drops potentially damaging movement components. Inspect all aspects of the winding system not just the click itself. Comprehensive inspection prevents multiple failure modes.

Modern German Movements

Modern German movements show click failures nearly as frequently as Sessions movements. The problems stem from cost-reduction measures affecting click design and materials. Thin components, marginal spring tensions, and inadequate riveting create reliability issues. These movements deserve the same cautious approach as Sessions movements.

German movements often use plastic components in click assemblies. Plastic wears faster than metal and can crack under stress. Inspect plastic clicks carefully for cracks or deformation. Replace questionable plastic clicks before failure. Metal replacement clicks are available for many applications providing improved reliability.

Don't assume modern means better regarding click design. Many modern movements sacrifice reliability for manufacturing cost. Treat unfamiliar modern movements with the same respect as vintage Sessions movements. Inspect thoroughly and wind carefully until you understand the specific movement's click system quality.

Developing Safe Winding Habits

Never Trust Sessions Clicks

The cardinal rule for Sessions movements is never trust the clicks without thorough inspection. This isn't unfair bias - it's recognition of documented design problems. Sessions clicks fail more frequently than other manufacturers' clicks. This fact is well-established through decades of clockmaker experience.

Inspect Sessions clicks during every service regardless of how well they seem to function. Check rivet tightness, click tip condition, spring tension, and ratchet wheel tooth condition. Replace any questionable components. Upgrade to shoulder rivets and steel springs. Prevention is far preferable to dealing with failure aftermath.

Don't wind Sessions clocks without addressing click systems first. It's not worth the injury risk. Some clockmakers refuse to service Sessions movements without click upgrades. While perhaps extreme, this position reflects the seriousness of the problem. At minimum, never wind a Sessions clock without complete click inspection.

Teaching Owners Safe Winding

Educate clock owners about proper winding technique when delivering serviced clocks. Demonstrate slow steady winding with click verification before releasing pressure. Explain why this technique matters. Most owners will follow guidance when they understand the reasons and risks.

Provide written winding instructions with delivered clocks. Simple cards explaining proper technique help owners remember correct procedures. Include warnings about click failure symptoms. Encourage owners to report unusual clicking sounds immediately rather than continuing to wind.

Some owners resist slowing down winding because they've always wound quickly. Explain that habits that worked for years can suddenly fail when clicks wear. The click that held reliably for decades may fail on the next winding. Safe practices protect against this inevitable progression.

Maintaining Professional Standards

Professional clockmakers never cut corners on click service. They inspect thoroughly, upgrade questionable components, and test repeatedly before returning clocks to customers. This standard protects both customers and professional reputations. A customer injured by click failure damages the clockmaker's business regardless of liability issues.

Document click inspections and upgrades in service records. Note rivet types, spring materials, and any modifications made. This documentation protects you if questions arise later. It also provides reference for future service on the same clock. Professional documentation demonstrates professional service.

Refuse to release clocks with questionable clicks. If an owner won't authorize proper repairs, don't return the clock in unsafe condition. Your professional judgment and ethics matter more than completing a specific job. Protect yourself and the owner from foreseeable accidents even if the owner doesn't appreciate the concern.

FAQs

Why did my Sessions clock click fail and hit my thumb during winding?

The click rivet loosened allowing the thin click to shift upward away from the ratchet wheel. This misalignment caused partial tooth engagement rather than full dropping into tooth spaces. The partial engagement rapidly wore the click tip. Eventually the worn tip slipped completely over teeth instead of catching. Mainspring power released through the winding key striking your thumb. Sessions movements are notorious for this problem due to thin ratchet wheels and clicks secured by straight rivets that inevitably loosen. The design is fundamentally flawed. Even slow careful winding won't prevent failure once click components wear sufficiently. The solution is replacing straight rivets with shoulder rivets, upgrading to steel click springs, and ensuring proper click tip condition before failure occurs.

How do I wind a clock safely to prevent click injuries?

Wind slowly with steady deliberate turns. Listen for each distinct click. After each turn, pause with tension on the key verifying the click holds before releasing pressure. Ease the click into gear rather than releasing suddenly - apply slight backward pressure feeling the catch. Only after confirming engagement should you reposition for the next turn. Never wind so rapidly that clicks blur together. Use let-down keys when winding unfamiliar clocks - the slotted design provides escape route if clicks fail. For Sessions movements specifically, never trust clicks without thorough inspection. Check rivet tightness, click tip condition, and spring tension. Replace any questionable components before winding. Safe winding habits combined with proper click maintenance prevent the painful dangerous click failures that can break fingers or damage movements.

What should I do if the click fails while I'm winding a clock?

Maintain firm grip on the key - don't release suddenly. You have mainspring power loaded with no click holding it. For preventing personal injury, the safest option is yanking the key quickly from the clock removing it from danger. However, this usually damages the clock through uncontrolled mainspring release. For mantel clocks, lay the clock on its back and slowly rotate the entire case unwinding the mainspring gradually. Case weight provides resistance for controlled release. For wall clocks, use both hands turning the key backward very slowly - half-turn at a time. This risks injury to both hands but may save the clock. If someone is available, have them steady the clock while you control the key. Don't attempt heroic clock saves at expense of your hands. Maintain perspective - clocks can be repaired but hand injuries are permanent.

Can I just retighten a loose Sessions click rivet?

Retightening worn straight rivets rarely provides lasting repair. By the time you notice looseness, both the rivet and click hole are worn to sloppy fit. The rivet can't be tightened adequately without binding click movement. You might achieve temporary improvement but the rivet will loosen again quickly. Proper repair requires replacing straight rivets with shoulder rivets. Shoulder rivets have precision-diameter shoulders matching click hole size and large heads distributing clamping force. They can be tightened securely without binding. Make custom shoulder rivets from steel rod - commercial clock supply rivets often don't fit Sessions applications well. Steel provides better strength than original brass rivets. Also inspect click tip and spring condition. Worn tips or weak springs require replacement regardless of rivet condition. Complete click system upgrade provides permanent reliability rather than repeated temporary fixes.

Why are Sessions movements more prone to click failures than other clocks?

Sessions used thin ratchet wheels and clicks compared to other manufacturers reducing material costs. The thin design makes click alignment critical - even slight rivet loosening shifts the click upward preventing full tooth engagement. Sessions also used straight rivets rather than shoulder rivets. Straight rivets are difficult to tighten properly and inevitably loosen over time as rivet and hole wear. The combination of thin components and inadequate rivets creates systemic reliability problems. Later Sessions movements added steel alignment disks over ratchet wheels helping maintain click position even with loose rivets. However, many Sessions movements lack these improvements. Modern German movements show similar problems from cost-reduction measures. The documented failure pattern isn't bias against Sessions - it's recognition of design flaws proven through decades of clockmaker experience and injured thumbs. Never trust Sessions clicks without thorough inspection and upgrade to shoulder rivets and steel springs.

Should I install two clicks on each ratchet wheel for safety?

Dual click installation provides redundancy where one click failure doesn't release the mainspring. This is perhaps overly cautious for most applications but provides peace of mind for clockmakers concerned about click reliability. Position dual clicks opposite each other on the ratchet wheel for balanced force distribution. Both clicks should engage simultaneously - if only one clicks, adjust positions. Use shoulder rivets and steel springs for both clicks. The redundancy is worthless if both clicks use weak original designs. One clockmaker's experience had a click spring fail but the backup prevented problems demonstrating redundancy value. However, proper single-click installation with shoulder rivets and steel springs typically provides adequate reliability. Dual clicks make most sense for movements with documented repeated failures or for clockmakers working on many Sessions movements where statistical probability of encountering failures is high.

What is a let-down key and when should I use one?

Let-down keys have slotted shafts that slip over winding squares rather than solid attachment. The slot allows controlled mainspring let-down or provides escape if clicks fail during winding. The wooden handle provides comfortable grip. While primarily designed as mainspring let-down tools, they provide excellent safety when winding unfamiliar clocks. If the click fails, the key won't spin violently because it's not solidly attached. You can release with one hand to retrieve the let-down tool from your pocket without losing complete control. Let-down keys come in narrow and wide slot sizes matching different winding square dimensions. Available from clock supply houses at modest cost. Keep one in your pocket when servicing multiple clocks. The small investment prevents injuries and demonstrates professional approach. Use let-down keys whenever winding clocks you don't know well or any Sessions movements regardless of familiarity.