Patient transport apparatus with steer lock assembly
A patient transport apparatus comprises a support structure comprising base, a frame, and a patient support surface to support a patient. The apparatus also includes at least one caster assembly coupled to the support structure, with each one of the caster assemblies comprising a wheel, a wheel support coupled to the wheel, and a steer lock assembly movable relative to the wheel support. An actuator is operatively coupled to the steer lock assembly to move the steer lock assembly between a non-steer locked and steer locked state to permit or prevent the wheel support and coupled wheel from swiveling about a swivel axis. The caster assemblies can also include a brake assembly coupled to the wheel, with the actuator operatively coupled to the brake assembly to move the brake assembly between a braked and unbraked state.
1 . A steer lock system for a patient transport apparatus, the steer lock system comprising:
a support structure;
a caster assembly coupled to the support structure to facilitate movement of the patient transport apparatus along a floor surface, the caster assembly including:
a wheel,
a wheel support coupled to the wheel to support the wheel for rotation about a rotational axis and for rotation about a swivel axis,
brake assembly including a brake plunger supported for movement along an axis, and a brake pad operatively attached to the brake plunger and arranged to selectively engage the wheel; and
a steer lock assembly movable relative to the wheel support and including a plunger spaced from the axis, a locking element coupled to the plunger and movable relative to the plunger, and a locking receiver; and
a foot pedal mounted to the support structure and rotatable relative to the support structure between:
a steer locked state defined with at least a portion of the foot pedal disposed in engagement with the plunger to limit rotation of the wheel support about the swivel axis with the locking element engaged with the locking receiver,
a non-steer locked state defined with the foot pedal disposed out of engagement with the plunger to permit the wheel support to swivel about the swivel axis with locking element disengaged from the locking receiver, and
a braked state defined with the foot pedal disposed out of engagement with the plunger and abutting the brake plunger to arrange the brake pad in engagement with the wheel to prevent the wheel from rotating about the rotational axis.
2 . The steer lock system of claim 1 , wherein the foot pedal is configured to move the steer lock assembly to the steer locked state from the non-steer locked state by applying a force on the plunger.
3 . The steer lock system of claim 1 , wherein the locking element is further defined as a steer lock pin coupled to the plunger and movable relative to the plunger.
4 . The steer lock system of claim 3 , wherein the locking receiver defines an opening to receive the steer lock pin in response to a force applied from the foot pedal engaging the plunger when the opening is axially aligned with the steer lock pin.
5 . The steer lock system of claim 4 , further including a first biasing device to bias the steer lock pin toward the opening in response to the force applied to the plunger, and a second biasing device to withdraw the steer lock pin from the opening in response to removal of the force applied to the plunger.
6 . The steer lock system of claim 5 , wherein the first biasing device is positioned between the plunger and the locking element, and the second biasing device is positioned between the plunger and the support structure.
7 . The steer lock system of claim 5 , wherein the foot pedal is operable to compress the first biasing device between the plunger and the steer lock pin when the opening is misaligned with the steer lock pin such that a biasing force continuously biases the steer lock pin against an upper surface of the locking receiver until the opening is axially aligned with the steer lock pin.
8 . The steer lock system of claim 5 , wherein the steer lock pin includes a stepped region having an upper step surface; and
wherein the plunger includes a lower portion having a lower portion surface, with the second biasing device positioned between the lower portion surface and the support structure.
9 . The steer lock system of claim 8 , wherein the plunger includes an upper portion having a terminal end surface arranged for engagement with the foot pedal in the steer locked state.
10 . The steer lock system of claim 9 , wherein the plunger includes a ledge portion between the lower portion and the upper portion and extending transverse to the lower portion and upper portion.
11 . The steer lock system of claim 10 , wherein the ledge portion includes:
an outer ledge portion, and
an inner ledge portion having an upper interior ledge surface and an opposing lower interior ledge surface, with the first biasing device being positioned between the lower interior ledge surface and the upper step surface.
12 . The steer lock system of claim 1 , wherein the foot pedal is operatively coupled to the brake assembly to move the brake assembly between:
an unbraked state permitting the wheel to rotate about the rotational axis to facilitate movement of the support structure along the floor surface, and
the braked state preventing the wheel from rotating about the rotational axis.
13 . The steer lock system of claim 12 , wherein the brake pad of the brake assembly is configured to disengage from the wheel in the unbraked state.
14 . The steer lock system of claim 1 , further including a first biasing device to bias the locking element toward the locking receiver in response to a force applied to the plunger from the foot pedal.
15 . The steer lock system of claim 14 , further including a second biasing device to withdraw the locking element from the locking receiver in response to removal of the force applied to the plunger.
16 . The steer lock system of claim 15 , wherein the first biasing device is positioned between the plunger and the locking element.
17 . The steer lock system of claim 16 , wherein the second biasing device is positioned between the plunger and the support structure.
18 . The steer lock system of claim 1 , wherein the plunger of the steer lock assembly is supported for movement in a direction arranged substantially parallel to the axis.
19 . A steer lock system for a patient transport apparatus, the steer lock system comprising:
a support structure;
a caster assembly coupled to the support structure to facilitate movement of the patient transport apparatus along a floor surface, the caster assembly including:
a wheel,
a wheel support coupled to the wheel to support the wheel for rotation about a rotational axis and for rotation about a swivel axis,
a steer lock assembly movable relative to the wheel support and including a plunger, a locking element coupled to the plunger and movable relative to the plunger, and a locking receiver;
a foot pedal mounted to the support structure and rotatable relative to the support structure between:
a steer locked state defined with at least a portion of the foot pedal disposed in engagement with the plunger to limit rotation of the wheel support about the swivel axis with the locking element engaged with the locking receiver, and
a non-steer locked state defined with the foot pedal disposed out of engagement with the plunger to permit the wheel support to swivel about the swivel axis with locking element disengaged from the locking receiver; and
a biasing device to withdraw the locking element from the locking receiver in response to removal of a force applied to the plunger from the foot pedal.