Dipper door latch with locking mechanism

Abstract

A dipper including a dipper door and an impact actuated jaw having a “C” shape defining a lip and a chin. The jaw is rotatably mounted on the dipper door for rotation between a door-opened position and a door-closed position and positioned so that when the jaw is in the door-opened position, the jaw chin can be impacted by the dipper body when the door pivots to the door-closed position. The dipper also includes a hold open mechanism for releasably holding the door latch in the latch open position when the latch is in the open position, and a locking mechanism for releasably locking the latch when the latch is in the door-closed position. The locking mechanism includes one bar pivotally attached to the door, and another bar pivotally connected to and extending between each of the one bar and the latch.

Description

BACKGROUND OF THE INVENTION [0001] The present invention relates to power shovels and, more particularly, to power shovels having a dipper adapted for excavating earthen material. Specifically, the present invention relates to latches for dipper doors. [0002] Large electric mining rope shovels utilize a digging attachment consisting of a stationary boom with a combination handle / dipper structure which mounts on the boom and actively crowds and hoists into a bank in order to dig with and fill the dipper. The dipper is rigidly connected to the handle. After digging through a bank face and filling with material, the dipper is lifted and the upper portion of the shovel is rotated relative to the lower portion of the shovel so that the dipper is positioned above a waiting dump truck. The operator then activates a tripping mechanism that opens a dipper door latch on the bottom of the dipper and allows a door to swing down and open. The contents of the dipper are then dumped into the truck...

AI Technical Summary

Benefits of technology

[0012] One object of the invention is to provide a new system that is less maintenance intensive.

[0013] Another object of the invention is to provide a new dipper door latch system that does not require replacement after a short amount of time.

[0014] Another object of the invention is to provide a dipper door latch mechanism that will eliminate almost all dry sliding contact surfaces by replacing translational sliding motion with rotational motions.

[0016] Another object of the invention is to provide a dipper latch mechanism that will latch with high reliability even when there is a “soft” impact between the dipper door and the dipper body.

[0017] Another object of the invention is to provide a dipper latch mechanism that will usually unlatch only when the operator wants to unlatch, avoiding any false and unwanted trips.

Problems solved by technology

This is a simple device including mainly two bars pulling on each other with dry, sliding friction contact that has worked well for many years; however, with the increase in dipper size over the past few years, its reliability has become compromised because dry sliding friction levels have increased under higher contact loads making behavior less predictable.

There are maintenance problems with this system, especially when it is used with 100-ton or larger payload dippers.

Latch bars and related operating equipment are a significant part of dipper maintenance cost.

The maintenance problems include broken pull chains and clevis.

The trip ropes have to be replaced constantly as they become frayed and strands break.

The tugger motor, gearing and drum take a continuous beating causing repeated failures.

And lastly, the latch bar has to have shimming added, and this is a constant ongoing maintenance issue that in the long run becomes labor intensive and costly.

The amount of tension required to trip or move a latch bar on a fully loaded 120-ton payload dipper nearly exceeds the mechanical ability of this system.

Larger motors are usually the solution, but the net result is a very high cost maintenance area.

Another problem with conventional mechanical latch closure mechanisms is the tendency for such mechanisms to quickly wear out and require replacement in only a short period of time.

Each time the slidable latch bar engages the latch keeper or the like, the tip of the slidable latch bar naturally wears down.

Since the latch bar is under very high load and the contact area is very small, the tip experiences very high contact forces that cause an accelerated rate of wear.

As the tip of the slidable latch bar wears down over time, it becomes possible for the dipper door to prematurely open before the power shovel operator is ready for the dipper door to open.

This, as can be appreciated by those skilled in the art, can create a hazardous and unsafe condition if the power shovel is not properly maintained.

Images