Open Loop Energy Inc. was founded more than 30 years ago as a hydraulic repair business for mining and construction machinery in the Southwest United States. But the company soon saw a need to manufacture a very specific component used on the bucket doors of the massive shovels used in these applications.
Critical yet often overlooked, the hydraulic snubber contributes to the reliable operation of the shovel doors. They act as a dampening device, controlling the movement and impact forces of the shovel door (also referred to as the dipper door) as it swings open and smoothly closes during the loading and dumping process. Without a properly functioning snubber, these doors, weighing up to 30,000 lb, can slam shut uncontrollably, causing severe structural damage and premature wear.
During the dumping phase, snubbers slow the swing of the dipper door as it opens, preventing it from slamming violently. Similarly, during reclosing, the snubber ensures the door settles back into place smoothly without shock loading the dipper structure.
While most dual-acting bucket door snubbers are manufactured directly by OEMs themselves, Open Loop Energy manufactures the HydroSnub, which offers longer life and control, said Dow White, Director of Business Development. Because the internal components, the housing, and in particular, advanced sealing, are manufactured in house, Open Loop has better control over the snubber’s efficiency, he said.
Open Loop’s advanced seals minimize bypass leakage, increasing efficiency and reliability. The closed system does not require an external fluid supply or pressurization, making it truly maintenance-free from the end-user perspective.
The HydroSnub reduces maintenance costs and boosts operator confidence. They do not require periodic servicing, lubrication, or adjustment. Maintenance needs are primarily limited to inspecting connecting pins. “It never requires maintenance,” Waite said. “The only maintenance is you have to keep the pin tight. If the pin comes out, you can have some serious damage.”
The HydroSnub controls and dampens the door’s swing, particularly when it opens to dump material into haul trucks and closes in preparation for the next load cycle. By controlling the momentum of the door, snubbers prevent uncontrolled motion that could otherwise lead to:
- Excessive structural wear on the dipper and connecting arms
- Damage to pin connections and latching mechanisms
- Time-consuming and costly repair or replacement of components
A hydraulic snubber consists of a rotary hydraulic actuator filled with oil and fitted with specially designed valves and orifices, said Waite. The snubber is attached between the dipper door and the shovel itself through a connecting arm or banana arm, he said. During operation, the arm swings with the motion of the door. The weight of the door movement creates pressure by compressing hydraulic oil in the actuator.
The oil passes through a series of precisely machined orifices, creating a controlled flow path that resists sudden motion. This controlled resistance slows the swing of the door, preventing uncontrolled impacts while ensuring smooth operation.
“As the door swings open, this arm now causes the compressed oil to move to the other side. The little orifices with the advanced sealing are designed to bypass,” Waite said. “It operates like airplane overhead bin doors. When you try to close your overhead bin, it kind of slows it. It’s the same principle as a shock absorber but it is rotary rather than a linear cylinder.”
HydroSnubs are are designed as direct replacement parts, offering compatibility across various OEM dipper configurations, including models from Komatsu and Caterpillar, said Waite. There are no complex modifications needed during retrofitting, reducing installation time and complexity.
Hydraulic snubbers are often seen as an improvement over traditional mechanical or disc-style snubbing systems. Some manufacturers still use friction-type disc snubbing systems which face considerable maintenance challenges, said Waite. Snubbers also minimize oil leakage, reducing wear over time. This results in a significantly longer service life, often spanning years under normal operating conditions.
Without a functioning snubber, uncontrolled door slams lead to extensive damage over time, requiring hundreds of hours for rebuilds. They prevent deformation and cracking, ensure longevity for pins, locks and other latching components, and reduce misalignment and other structural issues.
By minimizing these impacts, hydraulic snubbers eliminate an estimated 100 to 200 hours of rebuild time for each door failure, Waite said.
Whether viewed as a retrofit upgrade or as part of a new design specification, hydraulic snubbers have proven themselves as a critical component that delivers clear operational benefits. For engineers, recognizing and specifying hydraulic snubbers can directly contribute to stronger, more efficient, and more reliable mining operations.
Open Loop Energy
openloop.net
Filed Under: Featured, Mobile Hydraulic Tips
