结论：脚踏板每天要动好几次，机构的磨损累积速度超过多数人的预期
轮椅使用者每次转移（上下轮椅）都要翻起或放下脚踏板，很多人还要把脚踏板整个卸下来。
按每天转移 6 到 10 次估算，一年就是两三千次动作，几年下来上万次。
这个频次在轮椅的活动部件里属于较高的，而脚踏板机构又往往结构轻巧，所以磨损和松动的累积比很多人预期得快。
它的失效后果也不轻：
翻转中失效。 使用者正在转移时脚踏板突然下落或脱落。
锁定失效。 使用中脚踏板意外翻转，脚失去支撑。
承力失效。 使用者用脚踏板借力站起时断裂。
脱落。 可拆卸式脚踏板在行进中脱落。
常见的失效形式
| 失效形式 | 成因 | 后果 |
|---|---|---|
| 铰接部位磨损 | 反复转动 | 旷量增大、异响 |
| 锁定机构失效 | 磨损、弹簧疲劳 | 意外翻转 |
| 卡扣断裂 | 塑料件疲劳 | 脚踏板脱落 |
| 支撑臂变形 | 过载或疲劳 | 高度改变、卡滞 |
| 紧固件松动 | 振动 | 旷量与异响 |
| 限位失效 | 磨损 | 翻转角度异常 |
「旷量增大」虽然不是突发失效，但它是安全隐患的前兆 ——旷量大到一定程度，锁定就不可靠了。
试验的设计思路
动作的模拟。 模拟实际的翻起和放下动作。
角度的覆盖。 从下限位置到上限位置的全行程。
速度的确定。 接近实际操作速度。
载荷的施加。 翻转时是否带载荷（通常空载翻转，但承力状态要另行考察）。
循环次数。 按预期使用寿命确定。
中间检查。 过程中定期检查，记录性能随循环次数的变化。
「中间检查」比只看最终结果有价值 ——记录每若干次循环后的旷量和操作力，能看出退化的趋势，而不只是「最后有没有坏」。
需要组合考察的项目
脚踏板的考察不止翻转耐久一项：
静态承载。 单侧和双侧站立时的承载能力。
冲击。 使用者踩踏时的冲击载荷。
翻转耐久。 反复翻转的机构耐久。
拆装耐久。 可拆卸式的反复拆装。
锁定可靠性。 锁定后在载荷下是否可靠。
高度调节耐久。 可调高度的调节机构。
角度调节耐久。 可调角度的机构。
「单侧站立」是需要考察的工况 ——使用者转移时常常只有一只脚踩在一侧脚踏板上，这时候是偏载，对机构的考验比双侧站立更严苛。
载荷与循环的确定
载荷的依据。 按标准规定或按预期使用推算。
循环次数的依据。 预期寿命内的动作次数，通常留有裕度。
载荷与循环的组合。 空载循环加定期的载荷检查。
加严的考虑。 是否需要加大载荷做加速试验。
加速的限度。 加速不能改变磨损机理。
「加速的限度」要注意 ——提高翻转频率可以缩短试验时间，但频率过高会改变润滑和发热状态，磨损机理可能与实际不同。
试验中的观察与记录
操作力的变化。 翻转所需的力随循环的变化。
旷量的变化。 铰接部位的间隙。
异响。 出现异响的时点。
磨损痕迹。 定期检查磨损部位。
锁定的可靠性。 定期检查锁定功能。
紧固件状态。 是否松动。
润滑状态。 润滑脂的流失或变质。
「操作力的变化」是有用的指标 ——操作力先减小（磨合和旷量增大）后增大（磨损导致卡滞），这个变化曲线能反映机构的状态演变。
判定的要点
功能保持。 试验后仍能正常翻转和锁定。
结构完整。 无断裂、无明显变形。
旷量在限内。 间隙不超过规定。
操作力在范围内。 不至于过重或过轻。
锁定可靠。 锁定后在规定载荷下不失效。
残余强度。 耐久试验后仍能通过静态承载。
「耐久后的残余强度」是重要的判定项 ——机构在完成寿命循环后，仍然应当能承受规定的静载，而不是刚好没坏。
设计上的常见薄弱点
塑料卡扣。 反复受力后疲劳断裂。
薄壁支撑臂。 减重设计带来的强度不足。
单点锁定。 一个锁点失效就完全失效。
无限位保护。 过度翻转导致机构损坏。
润滑不足。 铰接部位无润滑或润滑易流失。
材料配对不当。 相同材料摩擦副容易咬合。
「单点锁定」的风险值得注意 ——建议在结构上考虑冗余或失效提示，让锁定失效不至于直接导致脚踏板下落。
常见的准备不足
信息不全。 材料、工艺、使用环境的信息缺失，导致方案设计缺乏依据。
样品不具代表性。 试制样品或挑选样品，与量产状态有差距。
条件未明确。 测试条件没说清楚，数据的适用范围就不明确。
只看初始值。 忽略了环境和时间作用后的性能变化。
项目不完整。 遗漏了必要的项目，提交时才发现。
这五项在实际委托中出现频率较高，建议在项目启动时逐项确认，因为它们造成的返工成本远高于事前确认所花的时间。
数据的组织与保存
记录的完整性。 条件、方法、设备、样品状态、实测值。
可追溯性。 数据与样品批次、生产批次的关联。
保存期限。 覆盖产品的生命周期。
检索的便利。 需要时能快速定位。
版本的管理。 数据更新时的版本控制。
建议建立统一的数据台账，记录每组数据的来源、条件、适用范围和有效期。数据积累起来之后，后续的产品开发和变更评估都能受益。
我们的做法
做脚踏板机构的耐久试验时，我们建议设置中间检查点，记录操作力和旷量随循环次数的变化，这比只看试验后的最终状态提供的信息多得多。
我们会把「耐久后的残余静载能力」作为判定项之一 ——因为完成循环而不断裂只是最低要求，残余强度才反映机构在寿命末期是否还安全。
对于可拆卸式脚踏板，拆装耐久我们建议单独做 ——反复拆装对卡扣和定位面的磨损与翻转磨损不是同一回事。
如果你的轮椅脚踏板机构需要安排耐久试验，可以把结构图和预期使用频次发过来一起定方案，或者直接联系：132 4819 8029。检测能力见服务介绍，产品分类见手动轮椅检测与电动轮椅检测，案例见案例。
English version
Conclusion. Every transfer into or out of a wheelchair requires the footrests to be swung up or lowered, and many users detach them entirely. At six to ten transfers a day, that is two or three thousand operations a year and tens of thousands over several years. This frequency is among the higher ones on a wheelchair, while footrest mechanisms tend to be lightly built, so wear and loosening accumulate faster than many expect. The consequences of failure are not trivial either. Failure during swinging drops or detaches the footrest while the user is transferring. Latch failure lets the footrest swing away in use, leaving the foot unsupported. Load failure breaks the footrest when a user pushes up from it to stand. And detachment loses a removable footrest while travelling.
Common failure modes. Pivot wear from repeated rotation produces increased free play and noise. Latch failure from wear and spring fatigue produces unintended swinging. Clip fracture from plastic fatigue detaches the footrest. Support arm distortion from overload or fatigue changes height and causes binding. Fastener loosening from vibration produces free play and noise. And stop failure from wear produces abnormal swing angles. Increasing free play is not a sudden failure while being a precursor to one: beyond a certain point, latching becomes unreliable.
Designing the test. Simulate the actual raising and lowering motion. Cover the full travel from the lower position to the upper position. Set a speed close to actual operation. Decide on loading during swinging, which is generally unloaded, with load-bearing conditions examined separately. Set the cycle count from expected service life. And build in intermediate checks, recording how performance changes with accumulated cycles. Intermediate checks are more valuable than the final result alone: recording free play and operating force every so many cycles shows the trend of degradation rather than merely whether it broke in the end.
Items to examine together. Footrest assessment extends beyond swing durability. Static loading covers capacity when standing on one side and on both. Impact covers the load when a user steps on it. Swing durability covers the mechanism under repeated operation. Attachment durability covers repeated removal and refitting on removable types. Latch reliability covers whether latching holds under load. Height adjustment durability covers the adjusting mechanism. And angle adjustment durability covers the angle mechanism. Single-side standing is a condition needing examination: users transferring frequently place only one foot on one footrest, and the resulting offset loading tests the mechanism more severely than standing on both.
Setting load and cycles. Base the load on the standard or on calculation from expected use. Base the cycle count on operations within the expected life, generally with margin. Combine the two, with unloaded cycling plus periodic loaded checks. Consider whether increased load is needed for acceleration. And observe the limits of acceleration, which must not change the wear mechanism. Those limits deserve attention: raising the cycling frequency shortens the test while too high a frequency alters lubrication and heating, so that the wear mechanism may differ from reality.
Observation and recording. Operating force and how it changes with cycles. Free play at the pivots. Noise and when it appears. Wear marks, inspected periodically. Latch reliability, checked periodically. Fastener condition and any loosening. And lubrication condition, covering loss or degradation of grease. Change in operating force is a useful indicator: it typically falls first as the mechanism beds in and free play grows, then rises as wear causes binding, and the shape of that curve reflects how the mechanism's condition evolves.
Points of judgement. Function retained, with normal swinging and latching after the test. Structure intact, without fracture or appreciable distortion. Free play within limits. Operating force within range, neither too heavy nor too light. Latching reliable, holding under the specified load. And residual strength, with the mechanism still passing static loading after durability testing. Residual strength after durability testing is an important criterion: completing the life cycles without breaking is the minimum, and residual strength is what shows whether the mechanism remains safe at the end of its life.
Common design weak points. Plastic clips fatigue and fracture under repeated loading. Thin-walled support arms lack strength through weight-saving design. Single-point latching fails completely when its one latch fails. Absent stops allow over-travel that damages the mechanism. Inadequate lubrication leaves pivots dry or loses grease readily. And poor material pairing lets identical materials gall against one another. Single-point latching deserves attention: consider redundancy or failure indication in the structure, so that latch failure does not drop the footrest directly.
How we handle it. For footrest mechanism durability testing we suggest intermediate check points, recording operating force and free play against accumulated cycles, which yields far more information than the final state alone. We treat residual static capacity after durability testing as one of the criteria, since completing the cycles without fracture is only the minimum and residual strength is what shows whether the mechanism remains safe at end of life. And for removable footrests we suggest testing attachment durability separately, since wear on clips and locating faces from repeated removal differs from wear from swinging.
If your footrest mechanism needs durability testing, send us the drawings and expected operating frequency and we will settle the approach. Phone or WeChat: +86 132 4819 8029.